When I switch the editor's language and values, the previous language error markers stick around. Fixes Microsoft/monaco-editor#475

src/languageFeatures.ts

@@ -92,7 +92,10 @@ export class DiagnostcsAdapter {
 		this._worker(resource).then(worker => {
 			return worker.doValidation(resource.toString()).then(diagnostics => {
 				const markers = diagnostics.map(d => toDiagnostics(resource, d));
-				monaco.editor.setModelMarkers(monaco.editor.getModel(resource), languageId, markers);
+				let model = monaco.editor.getModel(resource);
+				if (model.getModeId() === languageId) {
+					monaco.editor.setModelMarkers(model, languageId, markers);
+				}
 			});
 		}).then(undefined, err => {
 			console.error(err);