func NewErrCredentialsMissingUsername() error {
	return errCredentialsMissingUsername{}
}
NewErrCredentialsMissingUsername creates a new error for
errCredentialsMissingUsername.
package credentials
const (
	errCredentialsNotFoundMessage = "credentials not found in native keychain"
	errCredentialsMissingServerURLMessage = "no credentials server URL"
	errCredentialsMissingUsernameMessage  = "no credentials username"
)
type errCredentialsNotFound struct{}
func (errCredentialsNotFound) Error() string {
	return errCredentialsNotFoundMessage
}
func NewErrCredentialsNotFound() error {
	return errCredentialsNotFound{}
}
func IsErrCredentialsNotFound(err error) bool {
	_, ok := err.(errCredentialsNotFound)
	return ok
}
func IsErrCredentialsNotFoundMessage(err string) bool {
	return err == errCredentialsNotFoundMessage
}
type errCredentialsMissingServerURL struct{}
func (errCredentialsMissingServerURL) Error() string {
	return errCredentialsMissingServerURLMessage
}
type errCredentialsMissingUsername struct{}
func (errCredentialsMissingUsername) Error() string {
	return errCredentialsMissingUsernameMessage
}
func NewErrCredentialsMissingServerURL() error {
	return errCredentialsMissingServerURL{}
}