QbsProjectManager: Fix project parsing crash

We called deleteLater() on the parser while immediately deleting an
object that was supposed to outlive the parser.
Amends 1231c9e546.

Change-Id: I7ada041c4047d86249c5bdefc0c53e70dcdd5140
Reviewed-by: Jarek Kobus <jaroslaw.kobus@qt.io>

src/plugins/qbsprojectmanager/qbsproject.cpp

@@ -518,7 +518,7 @@ void QbsBuildSystem::handleQbsParsingDone(bool success)
         m_qbsUpdateFutureInterface->reportCanceled();
     }
 
-    m_qbsProjectParser->deleteLater();
+    m_qbsProjectParser->deleteLaterSafely();
     m_qbsProjectParser = nullptr;
     m_qbsUpdateFutureInterface->reportFinished();
     delete m_qbsUpdateFutureInterface;

src/plugins/qbsprojectmanager/qbsprojectparser.h

@@ -30,6 +30,9 @@ public:
     void cancel();
     Utils::Environment environment() const { return m_environment; }
 
+    // FIXME: Why on earth do we not own the FutureInterface?
+    void deleteLaterSafely() { m_fi = nullptr; deleteLater(); }
+
     QbsSession *session() const { return m_session; }
     QJsonObject projectData() const { return m_projectData; }
     ErrorInfo error() const { return m_error; }