remove unnecessary error return type after using log.Fatalf()

[kaanburaksener]

NewAdapter(driverName, dataSourceName string) function has only one return statement located at the end of the body, it always returns nil for error, and two error cases were covered by calling log.Fatalf() so we can remove the error type from the method signature along with the places we call NewAdapter() method as a small clean up.

[kantancoding]

@kaanburaksener Good catch! I'm wondering if it might be better to just return the error instead of calling os.Exit(1) within the factory function. That way we aren't delegating the control of application termination away from main.go. What do you think?

[kaanburaksener]

@selikapro Sounds good to me as well. On the other hand, I see the usage of log.Fatalf() in some other places (like in Run() method in server.go) as well so if you would like to delegate the termination of the app to main.go, then you should introduce this change in the whole repo.