Viper Viper errors should honor errors.Is() from standard package errors

It would be very nice and consistent with the modern ways of processing errors if viper's errors would follow the Unwrap/Is interfaces from the standard errors package.

Describe the solution you'd like to see This would allow the error checking to look like this:

if errors.Is(err, viper.ConfigFileNotFoundError{}) {
  // do something when there is no config file
} else if err != nil {
  // do something when there is a "real" error
}

var actual *viper.ConfigFileNotFoundError

if errors.As(err, &actual) {
  // Do something more meaningful!
  fmt.Printf("File: %s\n", actual.name)
}

I know it could be a matter of taste but since go introduced these funcs and interfaces, it would be nice to have them

Comment From: github-actions[bot]

👋 Thanks for reporting!

A maintainer will take a look at your issue shortly. 👀

In the meantime: We are working on Viper v2 and we would love to hear your thoughts about what you like or don't like about Viper, so we can improve or fix those issues.

⏰ If you have a couple minutes, please take some time and share your thoughts: https://forms.gle/R6faU74qPRPAzchZ9

📣 If you've already given us your feedback, you can still help by spreading the news, either by sharing the above link or telling people about this on Twitter:

https://twitter.com/sagikazarmark/status/1306904078967074816

Thank you! ❤️

Comment From: debarshiray

```go var actual *viper.ConfigFileNotFoundError

if errors.As(err, &actual) { // Do something more meaningful! fmt.Printf("File: %s\n", actual.name) } ```

As far as I can see, this variation works:

var actual viper.ConfigFileNotFoundError

if errors.As(err, &actual) {
  // Do something more meaningful!
  fmt.Printf("File: %s\n", actual.name)
}

Note that actual is not a pointer, because ConfigFileNotFoundError implements the error interface using a non-pointer receiver:

func (fnfe ConfigFileNotFoundError) Error() string {
        return fmt.Sprintf("Config File %q Not Found in %q", fnfe.name, fnfe.locations)
}

Comment From: debarshiray

Maybe this can be closed?

Comment From: ysulyma

@debarshiray the variation works for errors.As(), not errors.Is(), so the issue should remain open