QmlJSPluginDumper: Prevent potential crash when no results in QFuture

Ensure we don't reference non-existing QFuture's result.

Change-Id: I57668390e6ca83ae30c0b1de3e3a083a344ddbaa
Reviewed-by: Christian Kandeler <christian.kandeler@qt.io>

src/libs/qmljs/qmljsplugindumper.cpp

@@ -427,6 +427,10 @@ QFuture<PluginDumper::DependencyInfo> PluginDumper::loadDependencies(const FileP
 
     Utils::onFinished(loadQmlTypeDescription(dependenciesPaths), const_cast<PluginDumper*>(this),
             [this, iface, visited](const QFuture<PluginDumper::QmlTypeDescription> &typesFuture) {
+        if (typesFuture.resultCount() == 0 || typesFuture.isCanceled()) {
+            iface->reportCanceled();
+            return;
+        }
         PluginDumper::QmlTypeDescription typesResult = typesFuture.result();
         FilePaths newDependencies = FileUtils::toFilePathList(typesResult.dependencies);