CS API reqs which time out produce execrable error messages.

[ara4n]

Steps to reproduce

1. Run /nick Matthew|away
2. Wait 90s or so
3. Get a dialog which looks like this:

Server error
fetch failed: Failed to fetch (matrix-client.matrix.org)

Outcome

What did you expect?

"Couldn't change display name: timed out"

or

"Couldn't change display name: something went wrong"

What happened instead?

"Server error: fetch failed: Failed to fetch (matrix-client.matrix.org)"

Operating system

macOS

Application version

today's nightly

How did you install the app?

No response

Homeserver

matrix.org

Will you send logs?

No

[ara4n]

see also #30554

[t3chguy]

I think the issue here will be if this is a Gateway timeout on the server side then CORS prevents us seeing that response, and we just get an opaque failure back, so the best we could do is

"Couldn't change display name: something went wrong"