Element-web: Error dialog leaks access_token if UserSettings fail

[ara4n]

e.g. if you are offline

[lampholder]

UGLY:

[lampholder]

Related: #5373, #4541

[grahamperrin]

From https://github.com/vector-im/riot-web/issues/6331:

… the application simply 'Can't load user settings' …

– and I'm almost certain that:

• there was the word CORS in the dialogue
• there was no token in the dialogue.

Postscript

Yep, no token in this case:

[t3chguy]

This has been fixed by my above PR