Visit https://en.m.wikipedia.org/wiki/Main_Page in Firefox, see the following exception in the console:
TypeError: $container is null TypeError: $container is null
Stack trace:
[object Object] load.php:176:614
logError https://en.m.wikipedia.org/w/load.php:176:614
handler https://en.m.wikipedia.org/w/load.php:154:965
jQuery.Callbacks/fire https://en.m.wikipedia.org/w/load.php:45:104
jQuery.Callbacks/self.fireWith https://en.m.wikipedia.org/w/load.php:46:431
jQuery.Callbacks/self.fire https://en.m.wikipedia.org/w/load.php:46:474
mw.track https://en.m.wikipedia.org/w/load.php:154:747
execute/runScript/< https://en.m.wikipedia.org/w/load.php:161:860
jQuery.Callbacks/fire https://en.m.wikipedia.org/w/load.php:45:104
jQuery.Callbacks/self.add https://en.m.wikipedia.org/w/load.php:45:656
.Deferred/promise.always https://en.m.wikipedia.org/w/load.php:46:865
execute/runScript https://en.m.wikipedia.org/w/load.php:161:514
execute/</checkCssHandles https://en.m.wikipedia.org/w/load.php:162:241
execute https://en.m.wikipedia.org/w/load.php:162:943
handlePending https://en.m.wikipedia.org/w/load.php:158:522
execute/runScript/markModuleReady https://en.m.wikipedia.org/w/load.php:161:90
execute/runScript/< https://en.m.wikipedia.org/w/load.php:161:702
jQuery.Callbacks/fire https://en.m.wikipedia.org/w/load.php:45:104
jQuery.Callbacks/self.add https://en.m.wikipedia.org/w/load.php:45:656
.Deferred/promise.always https://en.m.wikipedia.org/w/load.php:46:865
execute/runScript https://en.m.wikipedia.org/w/load.php:161:514
execute/</checkCssHandles https://en.m.wikipedia.org/w/load.php:162:241
execute/</cssHandle/< https://en.m.wikipedia.org/w/load.php:162:371
jQuery.Callbacks/fire https://en.m.wikipedia.org/w/load.php:45:104
jQuery.Callbacks/self.fireWith https://en.m.wikipedia.org/w/load.php:46:431
jQuery.Callbacks/self.fire https://en.m.wikipedia.org/w/load.php:46:474
fireCallbacks https://en.m.wikipedia.org/w/load.php:156:505
addEmbeddedCSS https://en.m.wikipedia.org/w/load.php:157:99
addEmbeddedCSS/cssBufferTimer< https://en.m.wikipedia.org/w/load.php:156:723