1882315 - Exception in the browser console when moving from parent process to multiprocess mode

Status: NEW

(DevTools :: Console, defect, P2)

Description

[Alexandre Poirot [:ochameau]]

STR:

• open any pdf in a tab, for example https://github.com/jgrahamc/www-proposal/raw/main/proposal.pdf
• open the browser toolbox
• switch between multiprocess to parent process and then multiprocess mode again

AR:
You get the following exception many times:
resource://devtools/client/webconsole/reducers/messages.js, line 894: TypeError: can't access property "groupId", message is undefined

ER:
No exception

Comment 1

[Alexandre Poirot [:ochameau]]

The exception comes from this code:
https://searchfox.org/mozilla-central/rev/098f910d0593b12a42089dd8f40dcd19d1121430/devtools/client/webconsole/reducers/messages.js#224-233

      const firstWarningMessageId = state.warningGroupsById.get(
        warningGroupMessageId
      )[0];
      const firstWarningMessage = state.mutableMessagesById.get(
        firstWarningMessageId
      );

Where firstWarningMessage is null, because state.warningGroupsById refers to a message that has been removed.

There might be an issue with removeMessageFromState as it never clears state.warningGroupsById:
https://searchfox.org/mozilla-central/rev/098f910d0593b12a42089dd8f40dcd19d1121430/devtools/client/webconsole/reducers/messages.js#957
Adding some code to also clear this Set introduces some other exception. So things are even more complex.

It might be also related to this code, having specifics about groups:
https://searchfox.org/mozilla-central/rev/098f910d0593b12a42089dd8f40dcd19d1121430/devtools/client/webconsole/reducers/messages.js#920-943