1635019 - JavaScript Error: "TypeError: can't access property "firstChild", container is undefined" {file: "chrome://messenger/content/customizableui/panelUI.js" line: 1324}]

Status: RESOLVED FIXED

(Thunderbird :: Mail Window Front End, defect)

Description

[ISHIKAWA, Chiaki]

Running mochitest of FULL DEBUG version of thunderbird
produces the following error.
120 at the beginning of line is the frequencey of occurences.

120 INFO Console message: [JavaScript Error: "TypeError: can't access property "firstChild", container is undefined" {file: "chrome://messenger/content/customizableui/panelUI.js" line: 1324}]

mozilla/comm/mail/components/customizableui/content/panelUI.js

updateAlerts() {
let tabmail = document.getElementById("tabmail");
let sideloaded = ExtensionsUI.sideloaded;
let updates = ExtensionsUI.updates;
let container = PanelUI.addonNotificationContainer;

while (container.firstChild) {    <=== here
  container.firstChild.remove();
}

I think the whole while-statement ought to be enclosed in a if
(conainer) check.

if (container) {
while (container.firstChild) {
container.firstChild.remove();
}
}

But I am not even sure if |PanelUI.addonNotificationContaier| can be
null when |updateAlerts()| is called. This may be an edge case.
Or this may be really a very bad bug.
And if it is null, we may have to do something special.
So I leave it to the people in the know to produce a patch.

BTW, this error is encountered AFTER the patch in
Bug 1634511 was applied.

Moral of the story. mochitest infrastructure/harness REALLY OUGHT TO FAIL a
test that produces JavaScript Error during its execution. PERIOD. (Or does it? I am new to mochitest. It is in place since last December.)

Comment 1

[Geoff Lankow (:darktrojan)]

Attachment: 1635019-container-is-undefined-1.diff

It's undefined because we're init'ing gExtensionsNotifications too early, before PanelUI. I've changed it so that it doesn't happen on load, instead, after PanelUI.init. Also tidied up the linter imports.

Comment 2

[Magnus Melin [:mkmelin]]

Comment on attachment 9158071 [details] [diff] [review]
1635019-container-is-undefined-1.diff

Review of attachment 9158071 [details] [diff] [review]:
-----------------------------------------------------------------

Great, r=mkmelin

Comment 3

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/comm-central/rev/cdb11b6187f0
Fix "container is undefined" error in panelUI.js. r=mkmelin

Comment 4

[Geoff Lankow (:darktrojan)]

Comment on attachment 9158071 [details] [diff] [review]
1635019-container-is-undefined-1.diff

We should take this. One less source of useless error messages.

Comment 5

[Wayne Mery (:wsmwk)]

Comment on attachment 9158071 [details] [diff] [review]
1635019-container-is-undefined-1.diff

Approved for beta

Comment 6

[Rob Lemley [:rjl]]

Thunderbird 78.0b4:
https://hg.mozilla.org/releases/comm-beta/rev/5eb5649458a8