Use fmt.Errorf, error strings should start lowercase

internal/backends/backends.go

@@ -17,7 +17,6 @@ Scotty. If not, see <https://www.gnu.org/licenses/>.
 package backends
 
 import (
-	"errors"
 	"fmt"
 	"reflect"
 	"strings"
@@ -54,8 +53,7 @@ func ResolveBackend[T interface{}](config *viper.Viper) (T, error) {
 	if implements {
 		result = backend.(T)
 	} else {
-		err = errors.New(
+		err = fmt.Errorf("backend %s does not implement %s", backendName, interfaceName)
-			fmt.Sprintf("Backend %s does not implement %s", backendName, interfaceName))
 	}
 
 	return result, err
@@ -93,7 +91,7 @@ func resolveBackend(config *viper.Viper) (string, models.Backend, error) {
 	backendName := config.GetString("backend")
 	backendType := knownBackends[backendName]
 	if backendType == nil {
-		return backendName, nil, fmt.Errorf("Unknown backend %s", backendName)
+		return backendName, nil, fmt.Errorf("unknown backend %s", backendName)
 	}
 	return backendName, backendType().FromConfig(config), nil
 }

internal/backends/backends_test.go

@@ -49,14 +49,14 @@ func TestResolveBackendUnknown(t *testing.T) {
 	config := viper.New()
 	config.Set("backend", "foo")
 	_, err := backends.ResolveBackend[models.ListensImport](config)
-	assert.EqualError(t, err, "Unknown backend foo")
+	assert.EqualError(t, err, "unknown backend foo")
 }
 
 func TestResolveBackendInvalidInterface(t *testing.T) {
 	config := viper.New()
 	config.Set("backend", "dump")
 	_, err := backends.ResolveBackend[models.ListensExport](config)
-	assert.EqualError(t, err, "Backend dump does not implement ListensExport")
+	assert.EqualError(t, err, "backend dump does not implement ListensExport")
 }
 
 func TestGetBackends(t *testing.T) {

internal/backends/lastfm/lastfm.go

@@ -16,7 +16,6 @@ Scotty. If not, see <https://www.gnu.org/licenses/>.
 package lastfm
 
 import (
-	"errors"
 	"fmt"
 	"net/url"
 	"sort"
@@ -223,8 +222,8 @@ func (b *LastfmApiBackend) ImportListens(export models.ListensResult, importResu
 					importResult.ImportErrors = append(importResult.ImportErrors, ignoreMsg)
 				}
 			}
-			errMsg := fmt.Sprintf("Last.fm import ignored %v scrobbles", count-accepted)
+			err := fmt.Errorf("last.fm import ignored %v scrobbles", count-accepted)
-			return importResult, errors.New(errMsg)
+			return importResult, err
 		}
 
 		importResult.UpdateTimestamp(listens[count-1].ListenedAt)

internal/backends/scrobblerlog/parser.go

@@ -24,7 +24,6 @@ package scrobblerlog
 import (
 	"bufio"
 	"encoding/csv"
-	"errors"
 	"fmt"
 	"io"
 	"strconv"
@@ -71,8 +70,7 @@ func Parse(data io.Reader, includeSkipped bool) (ScrobblerLog, error) {
 		// We consider only the last field (recording MBID) optional
 		if len(row) < 7 {
 			line, _ := tsvReader.FieldPos(0)
-			return result, errors.New(fmt.Sprintf(
+			return result, fmt.Errorf("invalid record in scrobblerlog line %v", line)
-				"Invalid record in scrobblerlog line %v", line))
 		}
 
 		rating := row[5]
@@ -132,15 +130,15 @@ func ReadHeader(reader *bufio.Reader, log *ScrobblerLog) error {
 		}
 
 		if len(line) == 0 || line[0] != '#' {
-			err = errors.New(fmt.Sprintf("Unexpected header (line %v)", i))
+			err = fmt.Errorf("unexpected header (line %v)", i)
 		} else {
 			text := string(line)
 			if i == 0 && !strings.HasPrefix(text, "#AUDIOSCROBBLER/1") {
-				err = errors.New(fmt.Sprintf("Not a scrobbler log file"))
+				err = fmt.Errorf("not a scrobbler log file")
 			}
 
 			timezone, found := strings.CutPrefix(text, "#TZ/")
-			if strings.HasPrefix(text, "#TZ/") {
+			if found {
 				log.Timezone = timezone
 			}