nat: ParsePort: improve error

Unwrap the error to don't include "strconv.ParseUint" in the
error message.

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

Author: thaJeztah

nat/nat.go

@@ -49,7 +49,7 @@ func ParsePort(rawPort string) (int, error) {
 	}
 	port, err := strconv.ParseUint(rawPort, 10, 16)
 	if err != nil {
-		return 0, err
+		return 0, fmt.Errorf("invalid port '%s': %w", rawPort, errors.Unwrap(err))
 	}
 	return int(port), nil
 }

nat/nat_test.go

@@ -16,7 +16,7 @@ func TestParsePort(t *testing.T) {
 			doc:     "invalid value",
 			input:   "asdf",
 			expPort: 0,
-			expErr:  `strconv.ParseUint: parsing "asdf": invalid syntax`,
+			expErr:  `invalid port 'asdf': invalid syntax`,
 		},
 		{
 			doc:     "empty value",
@@ -32,7 +32,7 @@ func TestParsePort(t *testing.T) {
 			doc:     "negative value",
 			input:   "-1",
 			expPort: 0,
-			expErr:  `strconv.ParseUint: parsing "-1": invalid syntax`,
+			expErr:  `invalid port '-1': invalid syntax`,
 		},
 		// FIXME currently this is a valid port. I don't think it should be.
 		// I'm leaving this test commented out until we make a decision.
@@ -52,7 +52,7 @@ func TestParsePort(t *testing.T) {
 			doc:     "value out of range",
 			input:   "65536",
 			expPort: 0,
-			expErr:  `strconv.ParseUint: parsing "65536": value out of range`,
+			expErr:  `invalid port '65536': value out of range`,
 		},
 	}