avoid NPE if toolwindow doesn't exists (no Debug toolwindow at this moment)

It is must not be real situation, such internal errors must be handled in context and some solution suggested to user (edit RC, for example)

platform/lang-api/src/com/intellij/execution/runners/ExecutionUtil.java

@@ -31,6 +31,7 @@ import com.intellij.openapi.application.ApplicationManager;
 import com.intellij.openapi.diagnostic.Logger;
 import com.intellij.openapi.project.Project;
 import com.intellij.openapi.ui.MessageType;
+import com.intellij.openapi.ui.Messages;
 import com.intellij.openapi.wm.ToolWindowManager;
 import com.intellij.ui.content.Content;
 import com.intellij.util.ObjectUtils;
@@ -65,18 +66,19 @@ public class ExecutionUtil {
                                           @NotNull final String toolWindowId,
                                           @NotNull String taskName,
                                           @NotNull ExecutionException e) {
-    if (e instanceof RunCanceledByUserException) return;
+    if (e instanceof RunCanceledByUserException) {
+      return;
+    }
 
     LOG.debug(e);
 
     String description = e.getMessage();
-    HyperlinkListener listener = null;
-
     if (description == null) {
       LOG.warn("Execution error without description", e);
       description = "Unknown error";
     }
 
+    HyperlinkListener listener = null;
     if ((description.contains("87") || description.contains("111") || description.contains("206")) &&
         e instanceof ProcessNotCreatedException &&
         !PropertiesComponent.getInstance(project).isTrueValue("dynamic.classpath")) {
@@ -110,7 +112,14 @@ public class ExecutionUtil {
     UIUtil.invokeLaterIfNeeded(new Runnable() {
       @Override
       public void run() {
-        ToolWindowManager.getInstance(project).notifyByBalloon(toolWindowId, MessageType.ERROR, fullMessage, null, finalListener);
+        ToolWindowManager toolWindowManager = ToolWindowManager.getInstance(project);
+        if (toolWindowManager.canShowNotification(toolWindowId)) {
+          //noinspection SSBasedInspection
+          toolWindowManager.notifyByBalloon(toolWindowId, MessageType.ERROR, fullMessage, null, finalListener);
+        }
+        else {
+          Messages.showErrorDialog(project, fullMessage, "");
+        }
         NotificationListener notificationListener = ObjectUtils.tryCast(finalListener, NotificationListener.class);
         ourNotificationGroup.createNotification(title, finalDescription, NotificationType.ERROR, notificationListener).notify(project);
       }