Qml/JS Console: Fix crash for expressions typed before connecting

Task-number: QTCREATORBUG-10689
Change-Id: Iebce5596ff1cd71a1cd35e57ec302a6343134245
Reviewed-by: Ulf Hermann <ulf.hermann@digia.com>
Reviewed-by: Aurindam Jana <aurindam.jana@digia.com>

src/plugins/debugger/qml/qmlinspectoragent.cpp

@@ -73,6 +73,9 @@ QmlInspectorAgent::QmlInspectorAgent(DebuggerEngine *engine, QObject *parent)
 quint32 QmlInspectorAgent::queryExpressionResult(int debugId,
                                                  const QString &expression)
 {
+    if (!m_engineClient)
+        return 0;
+
     if (debug)
         qDebug() << __FUNCTION__ << '(' << debugId << expression
                  << m_engine.debugId() << ')';