summary: Ignore invalid JSON data when loading page

If the hash is e.g. `:class:*', it tries to parse it, which is
invalid.  There's a better solution to this problem, but I don't have time
to test possibly messing this up right now.

* src/current/scripts/entry-form.js (begin): Ignore JSON parsing errors.

src/current/scripts/entry-form.js

@@ -2140,7 +2140,7 @@ var client = ( function()
             }
             catch ( e )
             {
-                alert( 'Failed setting param values from URL.\n\n' + e.message );
+                // probably not the type of data we're looking for; just ignore
             }
         }