1579832 - JavaScript error: resource://formautofill/FormAutofillHandler.jsm, line 1000: TypeError: this.form.rootElement.ownerGlobal is null

Status: RESOLVED WORKSFORME

(Toolkit :: Form Autofill, defect, P2)

Description

[Rob Wu [:robwu]]

In log files of tests that open and close tabs (e.g. toolkit/components/extensions/test/browser/browser_ext_themes_ntp_colors.js), the following error appears repeatedly:

JavaScript error: resource://formautofill/FormAutofillHandler.jsm, line 1000: TypeError: this.form.rootElement.ownerGlobal is null

source of FormAutofillHandler.jsm, line 1000

FormAutofillHandler is constructed in FormAutofillContent.identifyAutofillFields

which is called here: https://searchfox.org/mozilla-central/rev/8ecd15049c11eb753717a6631213ba5ecc90e123/browser/extensions/formautofill/content/FormAutofillFrameScript.js#51

That happens after a setTimeout, and I can imagine that if the document unloads before the scheduled task has run, that the _nextHandleElement is a disconnected DOM element, and therefore causes the error.

This flaw is not only causing error message in the console; based on code inspection it may also cause memory leaks (of the DOM element) and prevent form detection from working (because the _hasPendingTask flag is never reset).

To fix this problem, _nextHandleElement should be cleared when the document onloads, and the logic in the setTimeout callback should return if _nextHandleElement has been unset (don't forget to clear _hasPendingTask though).

Comment 1

[Matthew N. [:MattN]]

Thanks for diagnosing!

Comment 2

[Tim Giles [:tgiles]]

When running the toolkit/components/extensions/text/browser/browser_ext_themes_ntp.colors.js test, this error no longer appears. So I tried browser/extensions/formautofill/test/unit/test_onFormSubmitted.js since this test calls identifyAutofillFields twice and still the error did not appear.

Closing as wfm