Aha, that's where the inspector is in Firefox. That's what I was looking for.
This is all there is in the logs immediately after selecting an item from the form popup/overlay. It causes the extension to crash and the vault to lock itself.
05:05:44.661 [OP] Locked at Thu Oct 13 2022 05:05:44 GMT-0400 (Eastern Daylight Saving Time) background.js:2:2282242
05:05:44.681 Uncaught (in promise) Error: Could not establish connection. Receiving end does not exist.
Ai moz-extension://0831b45a-2104-422a-a4fb-4ec2b078b545/background/background.js:2
background.js:2:1060123
Ai moz-extension://0831b45a-2104-422a-a4fb-4ec2b078b545/background/background.js:2
AsyncFunctionThrow self-hosted:811
(Async: async)
Xye moz-extension://0831b45a-2104-422a-a4fb-4ec2b078b545/background/background.js:2
InterpretGeneratorResume self-hosted:1819
AsyncFunctionNext self-hosted:807
(Async: async)
Ude moz-extension://0831b45a-2104-422a-a4fb-4ec2b078b545/background/background.js:2
Dde moz-extension://0831b45a-2104-422a-a4fb-4ec2b078b545/background/background.js:2
AsyncFunctionNext self-hosted:807
(Async: async)
xde moz-extension://0831b45a-2104-422a-a4fb-4ec2b078b545/background/background.js:2
InterpretGeneratorResume self-hosted:1819
AsyncFunctionNext self-hosted:807
(Async: async)
kye moz-extension://0831b45a-2104-422a-a4fb-4ec2b078b545/background/background.js:2
kye moz-extension://0831b45a-2104-422a-a4fb-4ec2b078b545/background/background.js:2
action moz-extension://0831b45a-2104-422a-a4fb-4ec2b078b545/background/background.js:2
Vse moz-extension://0831b45a-2104-422a-a4fb-4ec2b078b545/background/background.js:2
r moz-extension://0831b45a-2104-422a-a4fb-4ec2b078b545/background/background.js:2
apply self-hosted:2736
raw resource://gre/modules/ExtensionCommon.jsm:2519
wrapResponse resource://gre/modules/ExtensionChild.jsm:225
responses resource://gre/modules/ExtensionChild.jsm:194
map self-hosted:221
emit resource://gre/modules/ExtensionChild.jsm:194
recvRuntimeMessage resource://gre/modules/ExtensionChild.jsm:376
recvRuntimeMessage self-hosted:1356
_recv resource://gre/modules/ConduitsChild.jsm:82
receiveMessage resource://gre/modules/ConduitsChild.jsm:188
As for the "diagnostic report", that seems to be only for apps, not the browser extension. I don't see any option in the extension's settings to generate a report.
Should I still send a support email? I didn't because there's nothing sensitive in these logs, so I figured I can just post it here.