IDEA-89236 do not show error message if debugging was cancelled

plugins/android/src/org/jetbrains/android/run/AndroidDebugRunner.java

@@ -102,7 +102,7 @@ public class AndroidDebugRunner extends DefaultProgramRunner {
       launcher.setRunDescriptor(runDescriptor);
     }
     if (runDescriptor == null) {
-      throw new ExecutionException("Can't run an application");
+      return null;
     }
     tryToCloseOldSessions(executor, project);
     runningState.getProcessHandler().putUserData(ANDROID_PROCESS_HANDLER, runDescriptor);