From bug 1707517 comment 9:

'''
TypeError: currUrl is null
isCurrentMessage chrome://openpgp/content/ui/enigmailMsgHdrViewOverlay.js:934
handleSMimeMessage chrome://openpgp/content/ui/enigmailMsgHdrViewOverlay.js:1244
handleSmime chrome://openpgp/content/modules/pgpmimeHandler.jsm:240
onStartRequest chrome://openpgp/content/modules/pgpmimeHandler.jsm:202
enigmailMsgHdrViewOverlay.js:934:1
'''

We should avoid the exception.

Pushed by mkmelin@iki.fi:
https://hg.mozilla.org/comm-central/rev/f6177d7407da
Fail gracefull if we fail to extract URL attributes enigmailMsgHdrViewOverlay.js isCurrentMessage(). r=mkmelin

Please request 92 (and later 91) uplift.

Comment on attachment 9232914 [details]
Bug 1722097 - Fail gracefull if we fail to extract URL attributes enigmailMsgHdrViewOverlay.js isCurrentMessage(). r=mkmelin

[Approval Request Comment]
User impact if declined: pointless console spew
Testing completed (on c-c, etc.): yes on c-c
Risk to taking this patch (and alternatives if risky): Not risky, just avoiding errors in the console.

Comment on attachment 9232914 [details]
Bug 1722097 - Fail gracefull if we fail to extract URL attributes enigmailMsgHdrViewOverlay.js isCurrentMessage(). r=mkmelin

[Triage Comment]
Approved for beta

Thunderbird 92.0b3:
https://hg.mozilla.org/releases/comm-beta/rev/607150ad89a1

Comment on attachment 9232914 [details]
Bug 1722097 - Fail gracefull if we fail to extract URL attributes enigmailMsgHdrViewOverlay.js isCurrentMessage(). r=mkmelin

[Triage Comment]
Approved for esr91

Thunderbird 91.0.3:
https://hg.mozilla.org/releases/comm-esr91/rev/0270f257d8e9