diff --git a/images/src/org/intellij/images/editor/impl/ImageEditorUI.java b/images/src/org/intellij/images/editor/impl/ImageEditorUI.java
index 15cb24b91fc0..5258e5d6a1af 100644
--- a/images/src/org/intellij/images/editor/impl/ImageEditorUI.java
+++ b/images/src/org/intellij/images/editor/impl/ImageEditorUI.java
@@ -44,6 +44,7 @@ import com.intellij.util.LazyInitializer;
 import com.intellij.util.ObjectUtils;
 import com.intellij.util.SVGLoader;
 import com.intellij.util.ui.JBUI;
+import com.intellij.util.ui.UIUtil;
 import org.intellij.images.ImagesBundle;
 import org.intellij.images.editor.ImageDocument;
 import org.intellij.images.editor.ImageDocument.ScaledImageProvider;
@@ -72,6 +73,7 @@ import java.awt.image.BufferedImage;
 import java.awt.image.ColorModel;
 import java.beans.PropertyChangeEvent;
 import java.beans.PropertyChangeListener;
+import java.util.Objects;
 
 /**
  * Image editor UI
@@ -156,7 +158,7 @@ final class ImageEditorUI extends JPanel implements DataProvider, CopyProvider,
       actionToolbar.setTargetComponent(this);
 
       toolbarPanel = actionToolbar.getComponent();
-      toolbarPanel.setBackground(JBColor.lazy(() -> getBackground()));
+      toolbarPanel.setBackground(JBColor.lazy(() -> Objects.requireNonNullElse(getBackground(), UIUtil.getPanelBackground())));
       toolbarPanel.addMouseListener(new FocusRequester());
     }
 
diff --git a/images/src/org/intellij/images/editor/impl/jcef/JCefImageViewerUI.kt b/images/src/org/intellij/images/editor/impl/jcef/JCefImageViewerUI.kt
index 15003ebcacd4..2ddf892f2da6 100644
--- a/images/src/org/intellij/images/editor/impl/jcef/JCefImageViewerUI.kt
+++ b/images/src/org/intellij/images/editor/impl/jcef/JCefImageViewerUI.kt
@@ -15,6 +15,7 @@ import com.intellij.ui.components.ZoomableViewport
 import com.intellij.ui.components.panels.NonOpaquePanel
 import com.intellij.util.ObjectUtils
 import com.intellij.util.ui.JBUI
+import com.intellij.util.ui.UIUtil
 import org.intellij.images.ImagesBundle
 import org.intellij.images.editor.actionSystem.ImageEditorActions
 import org.intellij.images.editor.impl.jcef.JCefImageViewer.Companion.isDebugMode
@@ -110,7 +111,7 @@ class JCefImageViewerUI(private val myContentComponent: Component,
     }
 
     val toolbarPanel = actionToolbar.component
-    toolbarPanel.background = JBColor.lazy { background }
+    toolbarPanel.background = JBColor.lazy { background ?: UIUtil.getPanelBackground()}
     val topPanel: JPanel = NonOpaquePanel(BorderLayout())
     topPanel.add(toolbarPanel, BorderLayout.WEST)
 
@@ -123,7 +124,7 @@ class JCefImageViewerUI(private val myContentComponent: Component,
     myViewPort.setLayout(CardLayout())
     myViewer.preferredFocusedComponent.addMouseWheelListener(MOUSE_WHEEL_LISTENER)
     myViewPort.add(myContentComponent, IMAGE_PANEL)
-    myContentComponent.background = JBColor.lazy { background }
+    myContentComponent.background = JBColor.lazy { background ?: UIUtil.getPanelBackground()}
 
     val errorLabel = JLabel(
       ImagesBundle.message("error.broken.image.file.format"),
diff --git a/platform/diff-impl/src/com/intellij/diff/tools/combined/CombinedDiffUI.kt b/platform/diff-impl/src/com/intellij/diff/tools/combined/CombinedDiffUI.kt
index b5c0d20ace0a..0a9dcb466a59 100644
--- a/platform/diff-impl/src/com/intellij/diff/tools/combined/CombinedDiffUI.kt
+++ b/platform/diff-impl/src/com/intellij/diff/tools/combined/CombinedDiffUI.kt
@@ -11,7 +11,7 @@ import java.awt.Insets
 
 internal object CombinedDiffUI {
   val MAIN_HEADER_BACKGROUND: Color = JBColor.lazy {
-    return@lazy if (ExperimentalUI.isNewUI()) JBUI.CurrentTheme.EditorTabs.background() else UIUtil.getPanelBackground()
+    if (ExperimentalUI.isNewUI()) JBUI.CurrentTheme.EditorTabs.background() else UIUtil.getPanelBackground()
   }
 
   val MAIN_HEADER_INSETS: Insets
diff --git a/platform/diff-impl/src/com/intellij/diff/util/DiffUtil.java b/platform/diff-impl/src/com/intellij/diff/util/DiffUtil.java
index c867b0611145..4f758f016e89 100644
--- a/platform/diff-impl/src/com/intellij/diff/util/DiffUtil.java
+++ b/platform/diff-impl/src/com/intellij/diff/util/DiffUtil.java
@@ -475,12 +475,11 @@ public final class DiffUtil {
     Color commentFg = JBColor.lazy(() -> {
       EditorColorsScheme scheme = EditorColorsManager.getInstance().getGlobalScheme();
       TextAttributes commentAttributes = scheme.getAttributes(DefaultLanguageHighlighterColors.LINE_COMMENT);
-      if (commentAttributes.getForegroundColor() != null && commentAttributes.getBackgroundColor() == null) {
-        return commentAttributes.getForegroundColor();
-      }
-      else {
-        return scheme.getDefaultForeground();
+      Color commentAttributesForegroundColor = commentAttributes.getForegroundColor();
+      if (commentAttributesForegroundColor != null && commentAttributes.getBackgroundColor() == null) {
+        return commentAttributesForegroundColor;
       }
+      return scheme.getDefaultForeground();
     });
     label.setForeground(commentFg);
 
diff --git a/platform/lang-impl/src/com/intellij/codeInsight/actions/ReaderModeActionProvider.kt b/platform/lang-impl/src/com/intellij/codeInsight/actions/ReaderModeActionProvider.kt
index 779e6d78b1c1..d8d90e5bdcad 100644
--- a/platform/lang-impl/src/com/intellij/codeInsight/actions/ReaderModeActionProvider.kt
+++ b/platform/lang-impl/src/com/intellij/codeInsight/actions/ReaderModeActionProvider.kt
@@ -99,7 +99,7 @@ private class ReaderModeActionProvider : InspectionWidgetActionProvider {
           }
         }
       }.also {
-        it.foreground = JBColor.lazy { editor.colorsScheme.getColor(FOREGROUND) ?: FOREGROUND.defaultColor }
+        it.foreground = JBColor.lazy { editor.colorsScheme.getColor(FOREGROUND) ?: FOREGROUND.defaultColor ?: UIUtil.getInactiveTextColor()}
         if (!SystemInfo.isWindows) {
           it.font = FontUIResource(it.font.deriveFont(it.font.style, it.font.size - JBUIScale.scale(2).toFloat()))
         }
diff --git a/platform/platform-api/src/com/intellij/execution/process/ColoredOutputTypeRegistryImpl.java b/platform/platform-api/src/com/intellij/execution/process/ColoredOutputTypeRegistryImpl.java
index c3eb2109c13d..92885d5e05a6 100644
--- a/platform/platform-api/src/com/intellij/execution/process/ColoredOutputTypeRegistryImpl.java
+++ b/platform/platform-api/src/com/intellij/execution/process/ColoredOutputTypeRegistryImpl.java
@@ -11,15 +11,16 @@ import com.intellij.openapi.util.Key;
 import com.intellij.openapi.util.text.StringUtil;
 import com.intellij.ui.JBColor;
 import com.intellij.util.containers.ContainerUtil;
+import com.intellij.util.ui.UIUtil;
 import org.jetbrains.annotations.NonNls;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
 import java.awt.*;
 import java.util.ArrayList;
-import java.util.Collections;
 import java.util.List;
 import java.util.Map;
+import java.util.Objects;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.function.Supplier;
 
@@ -131,7 +132,7 @@ public final class ColoredOutputTypeRegistryImpl extends ColoredOutputTypeRegist
   }
 
   private static Color getColorByKey(TextAttributesKey colorKey) {
-    return JBColor.lazy(() -> EditorColorsManager.getInstance().getGlobalScheme().getAttributes(colorKey).getForegroundColor());
+    return JBColor.lazy(() -> Objects.requireNonNullElse(EditorColorsManager.getInstance().getGlobalScheme().getAttributes(colorKey).getForegroundColor(), UIUtil.getListForeground()));
   }
 
   private static @NotNull Color getDefaultForegroundColor() {
@@ -307,7 +308,7 @@ public final class ColoredOutputTypeRegistryImpl extends ColoredOutputTypeRegist
     return new ConsoleViewContentType(attribute, attrs);
   }
 
-  private static Color getColor(int colorIndex, Color enforcedColor, Supplier<? extends Color> getDefaultColor) {
+  private static Color getColor(int colorIndex, Color enforcedColor, @NotNull Supplier<? extends @NotNull Color> getDefaultColor) {
     if (enforcedColor != null) {
       return enforcedColor;
     }
diff --git a/platform/platform-impl/src/com/intellij/ide/ui/UITheme.kt b/platform/platform-impl/src/com/intellij/ide/ui/UITheme.kt
index af04505f392b..f5737b523186 100644
--- a/platform/platform-impl/src/com/intellij/ide/ui/UITheme.kt
+++ b/platform/platform-impl/src/com/intellij/ide/ui/UITheme.kt
@@ -391,7 +391,7 @@ private fun addPattern(key: String?, value: Any?, defaults: UIDefaults) {
   }
 }
 
-internal class IJColorUIResource(color: Color?, private val name: String) : JBColor(Supplier { color }), UIResource {
+internal class IJColorUIResource(color: Color, private val name: String) : JBColor(Supplier { color }), UIResource {
   override fun getName(): String = name
 
   override fun toString(): String = "IJColorUIResource(color=${super.toString()}, name=$name)"
diff --git a/platform/platform-impl/src/com/intellij/openapi/fileEditor/TextEditorWithPreview.java b/platform/platform-impl/src/com/intellij/openapi/fileEditor/TextEditorWithPreview.java
index 4f9f43e22bc3..1e2c34a4ac7e 100644
--- a/platform/platform-impl/src/com/intellij/openapi/fileEditor/TextEditorWithPreview.java
+++ b/platform/platform-impl/src/com/intellij/openapi/fileEditor/TextEditorWithPreview.java
@@ -47,6 +47,7 @@ import java.beans.PropertyChangeEvent;
 import java.beans.PropertyChangeListener;
 import java.util.HashMap;
 import java.util.Map;
+import java.util.Objects;
 import java.util.function.Supplier;
 
 import static com.intellij.openapi.actionSystem.ActionPlaces.TEXT_EDITOR_WITH_PREVIEW;
@@ -144,7 +145,7 @@ public class TextEditorWithPreview extends UserDataHolderBase implements TextEdi
     mySplitter.setFirstComponent(myEditor.getComponent());
     mySplitter.setSecondComponent(myPreview.getComponent());
     mySplitter.setDividerWidth(ExperimentalUI.isNewUI() ? 1 : 2); // We're using OnePixelSplitter, but it actually supports wider dividers.
-    mySplitter.getDivider().setBackground(JBColor.lazy(() -> EditorColorsManager.getInstance().getGlobalScheme().getColor(EditorColors.PREVIEW_BORDER_COLOR)));
+    mySplitter.getDivider().setBackground(JBColor.lazy(() -> Objects.requireNonNullElse(EditorColorsManager.getInstance().getGlobalScheme().getColor(EditorColors.PREVIEW_BORDER_COLOR), UIUtil.getPanelBackground())));
 
     myToolbarWrapper = createSplitEditorToolbar(mySplitter);
 
diff --git a/platform/platform-impl/src/com/intellij/ui/components/DefaultLinkButtonUI.kt b/platform/platform-impl/src/com/intellij/ui/components/DefaultLinkButtonUI.kt
index c3ba657cafab..20e55b844cb6 100644
--- a/platform/platform-impl/src/com/intellij/ui/components/DefaultLinkButtonUI.kt
+++ b/platform/platform-impl/src/com/intellij/ui/components/DefaultLinkButtonUI.kt
@@ -190,7 +190,7 @@ private fun getTextColor(button: AbstractButton) = when {
   else -> button.foreground ?: getLinkColor(button)
 }
 
-private fun getLinkColor(button: AbstractButton) = when {
+private fun getLinkColor(button: AbstractButton): Color = when {
   isPressed(button) -> Link.Foreground.PRESSED
   isHovered(button) -> Link.Foreground.HOVERED
   isVisited(button) -> Link.Foreground.VISITED
diff --git a/platform/platform-impl/src/com/intellij/util/ui/ButtonlessScrollBarUI.java b/platform/platform-impl/src/com/intellij/util/ui/ButtonlessScrollBarUI.java
index 41e7d7ea1ee7..49c8b59d16de 100644
--- a/platform/platform-impl/src/com/intellij/util/ui/ButtonlessScrollBarUI.java
+++ b/platform/platform-impl/src/com/intellij/util/ui/ButtonlessScrollBarUI.java
@@ -15,6 +15,7 @@ import com.intellij.ui.scale.JBUIScale;
 import com.intellij.util.Alarm;
 import com.intellij.util.MethodHandleUtil;
 import com.intellij.util.concurrency.SynchronizedClearableLazy;
+import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
 import javax.swing.*;
@@ -42,7 +43,7 @@ public class ButtonlessScrollBarUI extends BasicScrollBarUI {
     return jbColor(Gray._230, UIUtil.getListBackground());
   }
 
-  private JBColor jbColor(final Color regular, final Color dark) {
+  private JBColor jbColor(@NotNull Color regular, @NotNull Color dark) {
     return JBColor.lazy(() -> isDark() ? dark : regular);
   }
 
diff --git a/platform/util/ui/src/com/intellij/ui/ColorUtil.java b/platform/util/ui/src/com/intellij/ui/ColorUtil.java
index cfd7942091a1..606e242ef03c 100644
--- a/platform/util/ui/src/com/intellij/ui/ColorUtil.java
+++ b/platform/util/ui/src/com/intellij/ui/ColorUtil.java
@@ -111,7 +111,7 @@ public final class ColorUtil {
     });
   }
 
-  private static Color wrap(@NotNull Color color, Supplier<? extends Color> func) {
+  private static Color wrap(@NotNull Color color, @NotNull Supplier<? extends @NotNull Color> func) {
     return color instanceof JBColor ? JBColor.lazy(func) : func.get();
   }
 
@@ -121,7 +121,7 @@ public final class ColorUtil {
   }
 
   public static @NotNull Color shift(final @NotNull Color c, final double d) {
-    Supplier<Color> func = () -> new Color(shift(c.getRed(), d), shift(c.getGreen(), d), shift(c.getBlue(), d), c.getAlpha());
+    Supplier<@NotNull Color> func = () -> new Color(shift(c.getRed(), d), shift(c.getGreen(), d), shift(c.getBlue(), d), c.getAlpha());
     return wrap(c, func);
   }
 
@@ -138,7 +138,7 @@ public final class ColorUtil {
 
   public static @NotNull Color toAlpha(@Nullable Color color, final int a) {
     final Color c = color == null ? Color.black : color;
-    Supplier<Color> func = () -> new Color(c.getRed(), c.getGreen(), c.getBlue(), a);
+    Supplier<@NotNull Color> func = () -> new Color(c.getRed(), c.getGreen(), c.getBlue(), a);
     return wrap(c, func);
   }
 
diff --git a/platform/util/ui/src/com/intellij/ui/JBColor.java b/platform/util/ui/src/com/intellij/ui/JBColor.java
index 4b97b0890a1a..36c067232179 100644
--- a/platform/util/ui/src/com/intellij/ui/JBColor.java
+++ b/platform/util/ui/src/com/intellij/ui/JBColor.java
@@ -51,7 +51,7 @@ public class JBColor extends Color {
   }
 
   @SuppressWarnings("LambdaUnfriendlyMethodOverload")
-  protected JBColor(@NotNull Supplier<? extends Color> function) {
+  protected JBColor(@NotNull Supplier<? extends @NotNull Color> function) {
     super(0);
     name = null;
     defaultColor = null;
@@ -80,7 +80,8 @@ public class JBColor extends Color {
     func = null;
   }
 
-  public static JBColor lazy(@NotNull Supplier<? extends Color> supplier) {
+  @NotNull
+  public static JBColor lazy(@NotNull Supplier<? extends @NotNull Color> supplier) {
     return new JBColor(supplier);
   }
 
diff --git a/platform/util/ui/src/com/intellij/ui/MixedColorProducer.java b/platform/util/ui/src/com/intellij/ui/MixedColorProducer.java
index c49e4e47d979..9155058494f9 100644
--- a/platform/util/ui/src/com/intellij/ui/MixedColorProducer.java
+++ b/platform/util/ui/src/com/intellij/ui/MixedColorProducer.java
@@ -10,8 +10,8 @@ import java.util.function.Supplier;
 /**
  * This is a color producer that allows dynamically mix two colors.
  */
-public final class MixedColorProducer implements Supplier<Color> {
-  private final Couple<Color> couple;
+public final class MixedColorProducer implements Supplier<@NotNull Color> {
+  private final Couple<@NotNull Color> couple;
   private double mixer;
   private Color cached;
   private int argb0;
@@ -68,10 +68,11 @@ public final class MixedColorProducer implements Supplier<Color> {
     if (mixer >= 1) return couple.second;
     updateFirstARGB();
     updateSecondARGB();
-    if (cached == null) {
+    Color result = cached;
+    if (result == null) {
       //noinspection UseJBColor
-      cached = new Color(mix(16), mix(8), mix(0), mix(24));
+      cached = result = new Color(mix(16), mix(8), mix(0), mix(24));
     }
-    return cached;
+    return result;
   }
 }
diff --git a/platform/xdebugger-impl/src/com/intellij/xdebugger/impl/ui/XDebuggerEditorBase.java b/platform/xdebugger-impl/src/com/intellij/xdebugger/impl/ui/XDebuggerEditorBase.java
index d096e7ed7782..0f9448ad63d6 100644
--- a/platform/xdebugger-impl/src/com/intellij/xdebugger/impl/ui/XDebuggerEditorBase.java
+++ b/platform/xdebugger-impl/src/com/intellij/xdebugger/impl/ui/XDebuggerEditorBase.java
@@ -61,9 +61,7 @@ import java.awt.event.KeyEvent;
 import java.awt.event.MouseAdapter;
 import java.awt.event.MouseEvent;
 import java.lang.ref.WeakReference;
-import java.util.Arrays;
-import java.util.Collection;
-import java.util.Collections;
+import java.util.*;
 import java.util.List;
 
 public abstract class XDebuggerEditorBase implements Expandable {
@@ -153,7 +151,7 @@ public abstract class XDebuggerEditorBase implements Expandable {
 
   protected JComponent addChooser(JComponent component) {
     BorderLayoutPanel panel = JBUI.Panels.simplePanel(component);
-    panel.setBackground(JBColor.lazy(() -> component.getBackground()));
+    panel.setBackground(JBColor.lazy(() -> Objects.requireNonNullElse(component.getBackground(), UIUtil.getPanelBackground())));
     panel.addToRight(myLanguageChooser);
     return panel;
   }