Fix to allow case where ID is removed from the text file.

src/plugins/qmldesigner/core/model/modelnode.cpp

@@ -169,7 +169,7 @@ static bool idContainsWrongLetter(const QString& id)
 
 bool ModelNode::isValidId(const QString &id)
 {
-    return !(id.isEmpty() || idContainsWrongLetter(id));
+    return id.isEmpty() || !idContainsWrongLetter(id);
 }
 
 void ModelNode::setId(const QString& id)

src/plugins/qmldesigner/core/model/texttomodelmerger.cpp

@@ -114,7 +114,7 @@ bool TextToModelMerger::load(const QByteArray &data, DifferenceHandler &differen
 
         setActive(false);
 
-        throw;
+        return false;
     }
 }