The QML component parser in qdoc doesn't report errors

The QML parser in qtdeclarative is used by qdoc to parser both .qml files and QML code snippets. Currently, it only reports errors found when parsing snippets. It should also report errors when parsing QML component files. If the QML parser detects an error when parsing a QML component file, the documentation for the component is not generated. That's the way the parser works. It first parses the file and builds a parse tree. It only traverses the tree if the parse was successful.