Fix error processing in 'LoginUtils.requireLogin'

[vrubezhny]

Error mesage: Cannot read properties of null (reading 'toLowerCase')

[codecov]

Codecov Report

Attention: 1 lines in your changes are missing coverage. Please review.

Comparison is base (caeada7) 33.12% compared to head (43995e6) 33.12%.
Report is 1 commits behind head on main.

Files	Patch %	Lines
src/util/loginUtil.ts	0.00%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #3782   +/-   ##
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  Coverage   33.12%   33.12%           
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  Files          84       84           
  Lines        6195     6195           
  Branches     1270     1270           
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  Hits         2052     2052           
  Misses       4143     4143           

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[datho7561]

I don't know how to reproduce this issue, but "Login" seems to still work after the change

[vrubezhny]

I don't know how to reproduce this issue, but "Login" seems to still work after the change

I was doing some context switching stuff on Friday, then left the app working through the weekend (putting my note to asleep and waking it up for a few times, thus loosing the connection to the cluster) so today I had to re-login to a cluster, but it looks like oc status wasn't available for some reason, so it's execution finished with an error not returning any result in stderr (its value was null). The PR fixes such a case.