Errors should be wrapped when possible

[ccoVeille]

-		return errors.New("error creating file")
+		return fmt.Errorf("error creating file: %w", err)

Originally posted by @ccoVeille in #302 (comment)

[EwenQuim]

It's in the cli, isn't it? Good idea

[ccoVeille]

It was at least in

func (e *Engine) saveOpenAPIToFile(jsonSpecLocalPath string, jsonSpec []byte) error {

The errors are replaced by new one instead of wrapping them

[EwenQuim]

Ah exactly!

Minor as it doesn't impact runtime requests, but should definitely be handled! I tag it as low prio

[dylanhitt]

Closed with #331. Greping through the code base there currently doesn't seem to be any other occurrences of this pattern.