From 2202dbbfabca7d36eb3e662fbbf3dfe31321efc9 Mon Sep 17 00:00:00 2001
From: =?utf8?q?Gerg=C5=91=20Tisza?= <tgr.huwiki@gmail.com>
Date: Wed, 14 Jan 2015 07:09:41 +0000
Subject: [PATCH] Allow subscribing to module loading exceptions

Provide access via mw.track to module loading errors which are
otherwise swallowed by mw.loader.

Bug: T513
Bug: T85263
Change-Id: Ifc13c207af36dc56be931a3b140063354513a4ec
---
 resources/src/mediawiki/mediawiki.js | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/resources/src/mediawiki/mediawiki.js b/resources/src/mediawiki/mediawiki.js
index 90b8503266..2e78c1c7cd 100644
--- a/resources/src/mediawiki/mediawiki.js
+++ b/resources/src/mediawiki/mediawiki.js
@@ -668,6 +668,23 @@
 		 */
 		loader: ( function () {
 
+			/**
+			 * Fired via mw.track on various resource loading errors.
+			 *
+			 * @event resourceloader_exception
+			 * @param {Error|Mixed} e The error that was thrown. Almost always an Error
+			 *   object, but in theory module code could manually throw something else, and that
+			 *   might also end up here.
+			 * @param {string} [module] Name of the module which caused the error. Omitted if the
+			 *   error is not module-related or the module cannot be easily identified due to
+			 *   batched handling.
+			 * @param {string} source Source of the error. Possible values:
+			 *   - style: stylesheet error (only affects old IE where a special style loading method
+			 *     is used)
+			 *   - load-callback: exception thrown by user callback
+			 *   - module-execute: exception thrown by module code
+			 */
+
 			/**
 			 * Mapping of registered modules.
 			 *
@@ -852,6 +869,7 @@
 								styleEl.styleSheet.cssText += cssText;
 							} catch ( e ) {
 								log( 'Stylesheet error', e );
+								mw.track( 'resourceloader.exception', { exception: e, source: 'stylesheet' } );
 							}
 						} else {
 							styleEl.appendChild( document.createTextNode( cssText ) );
@@ -1115,6 +1133,8 @@
 							// A user-defined callback raised an exception.
 							// Swallow it to protect our state machine!
 							log( 'Exception thrown by user callback', e );
+							mw.track( 'resourceloader.exception',
+								{ exception: e, module: module, source: 'load-callback' } );
 						}
 					}
 				}
@@ -1242,6 +1262,7 @@
 						// and not in debug mode, such as when a symbol that should be global isn't exported
 						log( 'Exception thrown by ' + module, e );
 						registry[module].state = 'error';
+						mw.track( 'resourceloader.exception', { exception: e, module: module, source: 'module-execute' } );
 						handlePending( module );
 					}
 				}
-- 
2.20.1