Logging out should not fail if we are already logged out

[wetneb]

Originally posted at OpenRefine/OpenRefine#2873 by @addshore

Describe the bug

If I am logged into wikidata, but my session expires or I get logged out for some reason I can not use the log out button in the app.

Current Results

When I do click logout I see the following in the console and the app continues to think that I am logged in.

17:33:56.920 [                   refine] GET /command/wikidata/login (9487ms)
17:33:56.948 [                   refine] POST /command/core/get-all-preferences (28ms)
17:33:58.792 [                   refine] GET /command/core/get-csrf-token (1844ms)
17:33:58.807 [                   refine] POST /command/wikidata/login (15ms)
17:33:59.078 [      connection_mananger] [assertuserfailed] You are no longer logged in, so the action could not be completed. (271ms)

This is probably due to the assertuser option being used for this login call?

Expected behaviour

Clicking the logout button in this situation should detect that I am no longer logged in and thus allow me to re login to the app.

Screenshots

Stuck here in the app, can not log out

Desktop:

• OS: Windows 10
• Browser Version: Firefox 76.0.1 (64-bit)
• JRE or JDK Version:

java version "1.8.0_91"
Java(TM) SE Runtime Environment (build 1.8.0_91-b14)
Java HotSpot(TM) 64-Bit Server VM (build 25.91-b14, mixed mode)

OpenRefine :

• Version 3.3

[wetneb]

I would either:

• make sure logout calls are made without assert= parameter - but perhaps that is not a good idea: do we still want to fail if I try to logout thinking I am logged in as Mary, but in fact I am logged in as John?
• catch assertuserfailed ourselves and pretend logout failed?
• document that this can happen and require our users to call checkCredentials before?