595729 - uncaught exception from restoreLastSession

Status: NEW

(Firefox :: Session Restore, defect)

Description

[Paul O'Shannessy [:zpao] (not bugmail, email directly)]

Error: uncaught exception: [Exception... "'[JavaScript Error: "aTabs[ex - 1] is undefined" {file: "jar:file:///Applications/Minefield.app/Contents/MacOS/omni.jar!/components/nsSessionStore.js" line: 2236}]' when calling method: [nsISessionStore::restoreLastSession]"  nsresult: "0x80570021 (NS_ERROR_XPC_JAVASCRIPT_ERROR_WITH_DETAILS)"  location: "JS frame :: chrome://browser/content/browser.js :: restoreLastSession :: line 12990"  data: yes]

This is happening consistently with a session I have in my nightly, I'll investigate with a debug build and track it down.

Comment 1

[Paul O'Shannessy [:zpao] (not bugmail, email directly)]

It's coming from here:
http://hg.mozilla.org/mozilla-central/file/tip/browser/components/sessionstore/src/nsSessionStore.js#l2251

Something related to TabCandy and being in a weird state with hidden tabs... Apparently I had 0 unhidden tabs, and so we try to access aTabs[-1] :(
I'll see if I can get some STR from a clean session.

Interesting that the error says "aTabs[ex - 1] is undefined" instead of what's actually in the code, which is "aTabs[unhiddenTabs - 1]" Perhaps something from TM/JM merge?

Comment 2

[Paul O'Shannessy [:zpao] (not bugmail, email directly)]

I haven't seen this since (though tbh, I also haven't really used that feature much). I haven't seen any reports of it either, but we haven't hit b7 yet so I'll leave this open until this feature goes out to a wider audience.