[refactoring] Evaluate frequent usage of zap.Fatal()

[theurichde]

tl;dr: usage of zap.Fatal() is hard for testing.

the root problem here is the frequent use of zap.Fatal() through the application code. This causes the test execution process to immediately terminate without collecting failure logging when any application error occurs. Since the zap logger is not initialized for test runs, it is difficult to see where the problem is happening without debugging. Debugging is hard since it worked 100% of the time on my machine, only failing in the GitLab Actions.

Referring to #160

Implementation

• Wrap zap logger initialization in an interface or factory
  • enables overriding Fatal() to log the stack trace and not exit in tests