Debugger: Fix crash on close while debugging

Task-number: QTCREATORBUG-15987
Change-Id: I510add216ec16c0c6622870f26c68c16e99769ed
Reviewed-by: hjk <hjk@theqtcompany.com>

src/plugins/debugger/debuggerplugin.cpp

@@ -2502,6 +2502,8 @@ void DebuggerPluginPrivate::setInitialState()
 
 void DebuggerPluginPrivate::updateState(DebuggerEngine *engine)
 {
+    if (m_shuttingDown)
+        return;
     QTC_ASSERT(engine, return);
     QTC_ASSERT(m_watchersView->model(), return);
     QTC_ASSERT(m_returnView->model(), return);
@@ -2647,6 +2649,8 @@ void DebuggerPluginPrivate::updateState(DebuggerEngine *engine)
 
 void DebuggerPluginPrivate::updateDebugActions()
 {
+    if (m_shuttingDown)
+        return;
     //if we're currently debugging the actions are controlled by engine
     if (m_currentEngine->state() != DebuggerNotReady)
         return;
@@ -2775,6 +2779,8 @@ QTreeView *inspectorView()
 
 void DebuggerPluginPrivate::showMessage(const QString &msg, int channel, int timeout)
 {
+    if (m_shuttingDown)
+        return;
     //qDebug() << "PLUGIN OUTPUT: " << channel << msg;
     QTC_ASSERT(m_logWindow, return);
     switch (channel) {

src/plugins/debugger/debuggerruncontrol.cpp

@@ -232,8 +232,11 @@ bool DebuggerRunControl::promptToStop(bool *optionalPrompt) const
             "Terminating the session in the current"
             " state can leave the target in an inconsistent state."
             " Would you still like to terminate it?");
-    return showPromptToStopDialog(tr("Close Debugging Session"), question,
-                                  QString(), QString(), optionalPrompt);
+    bool result = showPromptToStopDialog(tr("Close Debugging Session"), question,
+                                         QString(), QString(), optionalPrompt);
+    if (result)
+        disconnect(this);
+    return result;
 }
 
 RunControl::StopResult DebuggerRunControl::stop()