various APIs: don't return null to avoid @Nullable being inferred if IDEA-173618 is fixed

java/debugger/impl/src/com/intellij/debugger/ui/tree/render/NodeRendererImpl.java

@@ -112,9 +112,8 @@ public abstract class NodeRendererImpl implements NodeRenderer{
       return cloned;
     }
     catch (CloneNotSupportedException e) {
-      LOG.error(e);
+      throw new RuntimeException(e); 
     }
-    return null;
   }
 
   @Override

platform/analysis-impl/src/com/intellij/codeInspection/ex/GlobalInspectionContextBase.java

@@ -122,8 +122,7 @@ public class GlobalInspectionContextBase extends UserDataHolderBase implements G
 
       final String[] availableProfileNames = profileManager.getAvailableProfileNames();
       if (availableProfileNames.length == 0) {
-        //can't be
-        return null;
+        throw new IllegalStateException("There should be at least one inspection profile");
       }
       profile = profileManager.getProfile(availableProfileNames[0], true);
     }

platform/core-api/src/com/intellij/openapi/progress/ProgressManager.java

@@ -60,9 +60,7 @@ public abstract class ProgressManager extends ProgressIndicatorProvider {
   public abstract <T> T runProcess(@NotNull Computable<T> process, @Nullable ProgressIndicator progress) throws ProcessCanceledException;
 
   @Override
-  public ProgressIndicator getProgressIndicator() {
-    return null;
-  }
+  public abstract ProgressIndicator getProgressIndicator();
 
   public static void progress(@NotNull String text) throws ProcessCanceledException {
     progress(text, "");