Nightly CI JS test coverage not found

[phil-davis]

https://drone.owncloud.com/owncloud/contacts/849/8/7

time="2021-06-10T01:09:55Z" level=error msg="Could not match files" error="file does not exist"

But an ordinary PR passes: https://github.com/owncloud/contacts/pull/713

Need to investigate.

[phil-davis]

https://drone.owncloud.com/owncloud/contacts/849/8/6

START:
10 06 2021 01:09:53.215:INFO [karma-server]: Karma v4.4.1 server started at http://0.0.0.0:9876/
10 06 2021 01:09:53.216:INFO [launcher]: Launching browsers firefox_custom with concurrency unlimited
10 06 2021 01:09:53.221:INFO [launcher]: Starting browser firefox via Remote WebDriver
10 06 2021 01:09:53.252:ERROR [WebDriver]: WebDriver command failed { spec:
   { platform: 'Linux',
     testName: 'Karma test',
     tags: [],
     version: '',
     base: 'WebDriver',
     browserName: 'firefox' },
  error:
   { Error: getaddrinfo ENOTFOUND selenium selenium:4444
       at GetAddrInfoReqWrap.onlookup [as oncomplete] (dns.js:56:26)
     errno: 'ENOTFOUND',
     code: 'ENOTFOUND',
     syscall: 'getaddrinfo',
     hostname: 'selenium',
     host: 'selenium',
     port: '4444' } }
10 06 2021 01:09:53.258:INFO [WebDriver]: Killed Karma test.
10 06 2021 01:09:53.259:ERROR [launcher]: Cannot start firefox via Remote WebDriver
    undefined

It had some problem starting Firefox. That happen 3 times - the nightly last night, and 2 restarts that I did.

But on the 3rd restart, it started Firefox OK and all passed!!!

So this seems to be an intermittent thing, probably not just on nightly pipelines.

Closing this issue because I don't really see what can be done here that will have a useful improvement.