Bug fixes Part 2

- If the internal v4l2 grabber is switched off, it will now be de-initialized (Issue: #542)
- Extended error detection in MJPEG decompress method
- Default instance capture activation if it is missing in the configuration (https://hyperion-project.org/goto/post?id=13656#post-13656)
- Fixed some small (think)mistakes (https://hyperion-project.org/threads/hdmi-grabber.3302/page-2#post-14887)

libsrc/hyperion/GrabberWrapper.cpp

@@ -104,11 +104,7 @@ void GrabberWrapper::handleSettingsUpdate(const settings::type& type, const QJso
 	if(type == settings::V4L2 || type == settings::SYSTEMCAPTURE)
 	{
 		// extract settings
-		QJsonObject obj;
-		if(config.isArray() && !config.isEmpty())
-			obj = config.array().at(0).toObject();
-		else
-			obj = config.object();
+		const QJsonObject& obj = config.object();
 
 		if(type == settings::SYSTEMCAPTURE  && !_grabberName.startsWith("V4L"))
 		{
@@ -172,5 +168,4 @@ void GrabberWrapper::handleSettingsUpdate(const settings::type& type, const QJso
 
 		}
 	}
-
 }