QmlProfiler: Avoid idle engine cancelling other engine's process

Task-number: QTCREATORBUG-9643

Change-Id: Ia0a2427a186fd9ad24e1cf620df48be13032a69b
Reviewed-by: Christian Stenger <christian.stenger@digia.com>
Reviewed-by: Kai Koehne <kai.koehne@digia.com>

src/plugins/qmlprofiler/qmlprofilerengine.cpp

@@ -249,6 +249,10 @@ void QmlProfilerEngine::cancelProcess()
 {
     QTC_ASSERT(d->m_profilerState, return);
 
+    // no process to be canceled? (there might be multiple engines, but only one runs a process)
+    if (!d->m_runner)
+        return;
+
     switch (d->m_profilerState->currentState()) {
     case QmlProfilerStateManager::AppReadyToStop : {
         d->m_profilerState->setCurrentState(QmlProfilerStateManager::AppStopped);