Fix completion conversion in case of errors

config/locales/en.yml

@@ -111,10 +111,10 @@ en:
               blank: Your username cannot be empty
   completions:
     edit:
-      title: "Edit completion"
+      title: Edit completion
     new:
-      title: "New completion"
-    singular: "completion"
+      title: New completion
+    singular: completion
   contests:
     edit:
       title: "Edit contest settings"
@@ -176,7 +176,7 @@ en:
     rank: Rank
   messages:
     convert:
-      title: "New completion"
+      title: New completion
     plural: "messages"
     singular: "message"
     warning: "You first need to add a puzzle before converting messages to completions."