always return a dummy model in plugin::getChildModel() for not crashing if something goes wrong

git-svn-id: https://lmms.svn.sf.net/svnroot/lmms/trunk/lmms@1677 0778d3d1-df1d-0410-868b-ea421aaaa00d

src/core/plugin.cpp

@@ -36,6 +36,7 @@
 #include "mixer.h"
 #include "config_mgr.h"
 #include "dummy_plugin.h"
+#include "automatable_model.h"
 
 
 static pixmapLoader __dummy_loader;
@@ -85,7 +86,8 @@ void plugin::loadFile( const QString & )
 
 automatableModel * plugin::getChildModel( const QString & )
 {
-	return NULL;
+	static floatModel fm;
+	return &fm;
 }