uMatrix extension console errors

[uBlock-user]

Description

Upon boot or upon disabling/enabling uMatrix, below mentioned errors appears in the extension console.

Uncaught (in promise) Error: First-Party Isolation is enabled, but the required 'firstPartyDomain' attribute was not set. (requirement -- Set privacy.firstparty.isolate in about:config to true)

Uncaught TypeError: can't access property "matches", µm.ubiquitousBlacklistRef is null

A specific URL where the issue occurs

about:devtools-toolbox?type=extension&id=uMatrix%40raymondhill.net

Steps to Reproduce

1. Disable/Enable uMatrix, browse to about:devtools-toolbox?type=extension&id=uMatrix%40raymondhill.net

2. Observe the aformentioned errors appear.

Supporting evidence

Your environment

• uMatrix version: 1.4.1b6
• Browser Name and version: Firefox 78/76
• Operating System and version: Win 10

[gwarser]

#209 -> gorhill/uMatrix#878 ?

[uBlock-user]

That would be the first error only, not the entire bug.

[Kein]

Can someone also fix this since I cant do pull requests:
https://github.com/gorhill/uMatrix/blob/master/platform/chromium/vapi-background.js#L278

if ( tab.id === -1 ) { return; }

to

if ( tab === null || tab.id === -1 ) { return; }

Collecting up to 2k errors per session