refactor: remove unused errors (#1093)

as per title

Co-authored-by: joel@joellee.org <joel@joellee.org>

internal/models/errors.go

@@ -11,10 +11,6 @@ func IsNotFoundError(err error) bool {
 		return true
 	case RefreshTokenNotFoundError, *RefreshTokenNotFoundError:
 		return true
-	case InstanceNotFoundError, *InstanceNotFoundError:
-		return true
-	case TotpSecretNotFoundError, *TotpSecretNotFoundError:
-		return true
 	case IdentityNotFoundError, *IdentityNotFoundError:
 		return true
 	case ChallengeNotFoundError, *ChallengeNotFoundError:
@@ -65,13 +61,6 @@ func (e RefreshTokenNotFoundError) Error() string {
 	return "Refresh Token not found"
 }
 
-// InstanceNotFoundError represents when an instance is not found.
-type InstanceNotFoundError struct{}
-
-func (e InstanceNotFoundError) Error() string {
-	return "Instance not found"
-}
-
 // FactorNotFoundError represents when a user is not found.
 type FactorNotFoundError struct{}
 
@@ -86,12 +75,6 @@ func (e ChallengeNotFoundError) Error() string {
 	return "Challenge not found"
 }
 
-type TotpSecretNotFoundError struct{}
-
-func (e TotpSecretNotFoundError) Error() string {
-	return "Totp Secret not found"
-}
-
 // SSOProviderNotFoundError represents an error when a SSO Provider can't be
 // found.
 type SSOProviderNotFoundError struct{}