Don't cache completion if a handler failed

package.json

@@ -55,7 +55,7 @@
         "c9"
     ],
     "c9plugins": {
-        "c9.ide.language": "#bf7c02e381",
+        "c9.ide.language": "#0a53cceabb",
         "c9.ide.language.css": "#8a77f72326",
         "c9.ide.language.generic": "#378d8a2127",
         "c9.ide.language.html": "#d831388dd2",