Improve Go code error handling

[r4victor]

Fixes #3229

This PR:

• Drops gerrors and tracerr in favor of standard Go error handling (fmt.Errorf/errors.New).
• Wraps most unwrapped errors with fmt.Errorf.
• Fixes code that both logs and propagates errors.
• Other error handling fixes.

The idea of this PR is to make error handling consistent and use standard Go. Most errors are propagated with fmt.Errorf("some action: %w", err) pattern, effectively building explicit call stack. In some places this may be redundant and verbose but it's still conventional Go error handling.