lint(errorlint): handle wrapped errors

Enable errorlint and preserve wrapped error chains so runtime checks
and tests classify failures correctly. This also makes Route53
surface insert failures instead of silently dropping them.

Signed-off-by: Ville Vesilehto <ville@vesilehto.fi>

plugin/file/file.go

@@ -167,7 +167,7 @@ func Parse(f io.Reader, origin, fileName string, serial int64) (*Zone, error) {
 		}
 	}
 	if zp.Err() != nil {
-		return nil, fmt.Errorf("failed to parse file %q for origin %s with error %v", fileName, origin, zp.Err())
+		return nil, fmt.Errorf("failed to parse file %q for origin %s with error %w", fileName, origin, zp.Err())
 	}
 	if !seenSOA {
 		return nil, fmt.Errorf("file %q has no SOA record for origin %s", fileName, origin)

plugin/file/reload.go

@@ -1,6 +1,7 @@
 package file
 
 import (
+	"errors"
 	"os"
 	"path/filepath"
 	"time"
@@ -30,7 +31,8 @@ func (z *Zone) Reload(t *transfer.Transfer) error {
 				zone, err := Parse(reader, z.origin, zFile, serial)
 				reader.Close()
 				if err != nil {
-					if _, ok := err.(*serialErr); !ok {
+					var serialErr *serialErr
+					if !errors.As(err, &serialErr) {
 						log.Errorf("Parsing zone %q: %v", z.origin, err)
 					}
 					continue