Changing error.php?mode=js from text/plain to text/javascript

Changing the js mimetype to text/javascript to avoid problems with some proxy configurations.

errors.php

@@ -35,7 +35,7 @@
 	$ERRORS[12] = __("SQL escaping test failed, check your database and PHP configuration");
 
 	if ($_REQUEST['mode'] == 'js') {
-		header("Content-Type: text/plain; charset=UTF-8");
+		header("Content-Type: text/javascript; charset=UTF-8");
 
 		print "var ERRORS = [];\n";