QML: Band-aid fix to prevent a crash

If the document that FindExportedCppTypes is to search is not in the
snapshot, skip over it (instead of passing the shared pointer with a
null-value inside).

Change-Id: I462e3d22aa4e1cc51e710c75ae0f9399c151240b
Reviewed-by: Ulf Hermann <ulf.hermann@qt.io>
Reviewed-by: Nikolai Kosjar <nikolai.kosjar@qt.io>

src/libs/qmljs/qmljsfindexportedcpptypes.cpp

@@ -31,6 +31,7 @@
 #include <cplusplus/TypeOfExpression.h>
 #include <cplusplus/cppmodelmanagerbase.h>
 #include <cplusplus/CppDocument.h>
+#include <utils/qtcassert.h>
 
 #include <QList>
 
@@ -819,6 +820,8 @@ FindExportedCppTypes::FindExportedCppTypes(const CPlusPlus::Snapshot &snapshot)
 
 QStringList FindExportedCppTypes::operator()(const CPlusPlus::Document::Ptr &document)
 {
+    QTC_ASSERT(!document.isNull(), return QStringList());
+
     m_contextProperties.clear();
     m_exportedTypes.clear();
     QStringList fileNames;

src/libs/qmljs/qmljsmodelmanagerinterface.cpp

@@ -1321,7 +1321,10 @@ void ModelManagerInterface::updateCppQmlTypes(QFutureInterface<void> &interface,
         if (!scan) {
             hasNewInfo = newData.remove(fileName) > 0 || hasNewInfo;
             foreach (const QString &file, newDeclarations[fileName]) {
-                finder(snapshot.document(file));
+                CPlusPlus::Document::Ptr doc = snapshot.document(file);
+                if (doc.isNull())
+                    continue;
+                finder(doc);
                 hasNewInfo = rescanExports(file, finder, newData) || hasNewInfo;
             }
             continue;