chore(all): wrap all sentinel errors

- Force to use `errors.Is` instead of `==` to compare errors

internal/configuration/settings/helpers/belong.go

@@ -22,7 +22,7 @@ var (
 
 func AreAllOneOf(values, choices []string) (err error) {
 	if len(values) > 0 && len(choices) == 0 {
-		return ErrNoChoice
+		return fmt.Errorf("%w", ErrNoChoice)
 	}
 
 	set := make(map[string]struct{}, len(choices))

internal/configuration/settings/openvpn.go

@@ -100,14 +100,14 @@ func (o OpenVPN) validate(vpnProvider string) (err error) {
 		vpnProvider != providers.VPNSecure
 
 	if isUserRequired && *o.User == "" {
-		return ErrOpenVPNUserIsEmpty
+		return fmt.Errorf("%w", ErrOpenVPNUserIsEmpty)
 	}
 
 	passwordRequired := isUserRequired &&
 		(vpnProvider != providers.Ivpn || !ivpnAccountID.MatchString(*o.User))
 
 	if passwordRequired && *o.Password == "" {
-		return ErrOpenVPNPasswordIsEmpty
+		return fmt.Errorf("%w", ErrOpenVPNPasswordIsEmpty)
 	}
 
 	err = validateOpenVPNConfigFilepath(isCustom, *o.ConfFile)
@@ -160,7 +160,7 @@ func validateOpenVPNConfigFilepath(isCustom bool,
 	}
 
 	if confFile == "" {
-		return ErrFilepathMissing
+		return fmt.Errorf("%w", ErrFilepathMissing)
 	}
 
 	err = helpers.FileExists(confFile)
@@ -186,7 +186,7 @@ func validateOpenVPNClientCertificate(vpnProvider,
 		providers.VPNSecure,
 		providers.VPNUnlimited:
 		if clientCert == "" {
-			return ErrMissingValue
+			return fmt.Errorf("%w", ErrMissingValue)
 		}
 	}
 
@@ -209,7 +209,7 @@ func validateOpenVPNClientKey(vpnProvider, clientKey string) (err error) {
 		providers.VPNUnlimited,
 		providers.Wevpn:
 		if clientKey == "" {
-			return ErrMissingValue
+			return fmt.Errorf("%w", ErrMissingValue)
 		}
 	}
 
@@ -227,7 +227,7 @@ func validateOpenVPNClientKey(vpnProvider, clientKey string) (err error) {
 func validateOpenVPNEncryptedKey(vpnProvider,
 	encryptedPrivateKey string) (err error) {
 	if vpnProvider == providers.VPNSecure && encryptedPrivateKey == "" {
-		return ErrMissingValue
+		return fmt.Errorf("%w", ErrMissingValue)
 	}
 
 	if encryptedPrivateKey == "" {

internal/configuration/settings/serverselection.go

@@ -118,7 +118,7 @@ func (ss *ServerSelection) validate(vpnServiceProvider string,
 	}
 
 	if *ss.FreeOnly && *ss.PremiumOnly {
-		return ErrFreePremiumBothSet
+		return fmt.Errorf("%w", ErrFreePremiumBothSet)
 	}
 
 	if *ss.StreamOnly &&

internal/configuration/settings/wireguard.go

@@ -52,7 +52,7 @@ func (w Wireguard) validate(vpnProvider string, ipv6Supported bool) (err error)
 
 	// Validate PrivateKey
 	if *w.PrivateKey == "" {
-		return ErrWireguardPrivateKeyNotSet
+		return fmt.Errorf("%w", ErrWireguardPrivateKeyNotSet)
 	}
 	_, err = wgtypes.ParseKey(*w.PrivateKey)
 	if err != nil {
@@ -75,7 +75,7 @@ func (w Wireguard) validate(vpnProvider string, ipv6Supported bool) (err error)
 
 	// Validate Addresses
 	if len(w.Addresses) == 0 {
-		return ErrWireguardInterfaceAddressNotSet
+		return fmt.Errorf("%w", ErrWireguardInterfaceAddressNotSet)
 	}
 	for i, ipNet := range w.Addresses {
 		if ipNet.IP == nil || ipNet.Mask == nil {

internal/configuration/settings/wireguardselection.go

@@ -41,7 +41,7 @@ func (w WireguardSelection) validate(vpnProvider string) (err error) {
 		// endpoint IP addresses are baked in
 	case providers.Custom:
 		if len(w.EndpointIP) == 0 {
-			return ErrWireguardEndpointIPNotSet
+			return fmt.Errorf("%w", ErrWireguardEndpointIPNotSet)
 		}
 	default: // Providers not supporting Wireguard
 	}
@@ -51,12 +51,12 @@ func (w WireguardSelection) validate(vpnProvider string) (err error) {
 	// EndpointPort is required
 	case providers.Custom:
 		if *w.EndpointPort == 0 {
-			return ErrWireguardEndpointPortNotSet
+			return fmt.Errorf("%w", ErrWireguardEndpointPortNotSet)
 		}
 	// EndpointPort cannot be set
 	case providers.Surfshark:
 		if *w.EndpointPort != 0 {
-			return ErrWireguardEndpointPortSet
+			return fmt.Errorf("%w", ErrWireguardEndpointPortSet)
 		}
 	case providers.Airvpn, providers.Ivpn, providers.Mullvad, providers.Windscribe:
 		// EndpointPort is optional and can be 0
@@ -92,7 +92,7 @@ func (w WireguardSelection) validate(vpnProvider string) (err error) {
 		// public keys are baked in
 	case providers.Custom:
 		if w.PublicKey == "" {
-			return ErrWireguardPublicKeyNotSet
+			return fmt.Errorf("%w", ErrWireguardPublicKeyNotSet)
 		}
 	default: // Providers not supporting Wireguard
 	}