Whenever a login is verified, the username should be checked

[pixtron]

Describe the bug

If there is a valid accessKey for user A in the key store, but the current active instance is user B's instance, it might happen, that the contents of user B are uploaded to the cloud of user A.

To Reproduce

Steps to reproduce the behavior:
1.) log in with user B
2.) stop client
3.) change accessKey in key store to a valid accessKey for user A
4.) start client

Expected behavior

the correct instance for the accessKey in the key store should be loaded.

Environment

• desktop client version: 1.2.1