When WikiEditor is installed, the unit tests show this exception in the console. This is because code is insufficiently separated and both providing APIs and running code intended for the EditPage, selecting elements that don't exist and ending up unconditionally emitting events on page load (regardless of wgAction).
[Edit] Missing property "editingSessionId" (anonymous function) @ ext.eventLogging.core.js:277 (anonymous function) mw.track mw.eventLog.prepare @ ext.eventLogging.core.js:192 mw.eventLog.logEvent @ ext.eventLogging.core.js:258 .. (anonymous function) @ load.php?modules=schema.Edit