chore(all): review error wrappings

- remove repetitive `cannot` and `failed` prefixes
- rename `unmarshaling` to `decoding`

internal/storage/read.go

@@ -14,7 +14,7 @@ import (
 
 // readFromFile reads the servers from server.json.
 // It only reads servers that have the same version as the hardcoded servers version
-// to avoid JSON unmarshaling errors.
+// to avoid JSON decoding errors.
 func (s *Storage) readFromFile(filepath string, hardcodedVersions map[string]uint16) (
 	servers models.AllServers, err error) {
 	file, err := os.Open(filepath)
@@ -40,7 +40,7 @@ func (s *Storage) extractServersFromBytes(b []byte, hardcodedVersions map[string
 	servers models.AllServers, err error) {
 	rawMessages := make(map[string]json.RawMessage)
 	if err := json.Unmarshal(b, &rawMessages); err != nil {
-		return servers, fmt.Errorf("cannot decode servers: %w", err)
+		return servers, fmt.Errorf("decoding servers: %w", err)
 	}
 
 	// Note schema version is at map key "version" as number
@@ -90,7 +90,7 @@ func (s *Storage) readServers(provider string, hardcodedVersion uint16,
 
 	err = json.Unmarshal(rawMessage, &versionObject)
 	if err != nil {
-		return servers, false, fmt.Errorf("cannot decode servers version for provider %s: %w",
+		return servers, false, fmt.Errorf("decoding servers version for provider %s: %w",
 			provider, err)
 	}
 
@@ -107,7 +107,7 @@ func (s *Storage) readServers(provider string, hardcodedVersion uint16,
 
 	err = json.Unmarshal(rawMessage, &servers)
 	if err != nil {
-		return servers, false, fmt.Errorf("cannot decode servers for provider %s: %w",
+		return servers, false, fmt.Errorf("decoding servers for provider %s: %w",
 			provider, err)
 	}
 

internal/storage/read_test.go

@@ -36,12 +36,12 @@ func Test_extractServersFromBytes(t *testing.T) {
 	}{
 		"bad JSON": {
 			b:          []byte("garbage"),
-			errMessage: "cannot decode servers: invalid character 'g' looking for beginning of value",
+			errMessage: "decoding servers: invalid character 'g' looking for beginning of value",
 		},
 		"bad provider JSON": {
 			b:                 []byte(`{"cyberghost": "garbage"}`),
 			hardcodedVersions: populateProviderToVersion(map[string]uint16{}),
-			errMessage: "cannot decode servers version for provider Cyberghost: " +
+			errMessage: "decoding servers version for provider Cyberghost: " +
 				"json: cannot unmarshal string into Go value of type struct { Version uint16 \"json:\\\"version\\\"\" }",
 		},
 		"bad servers array JSON": {
@@ -49,7 +49,7 @@ func Test_extractServersFromBytes(t *testing.T) {
 			hardcodedVersions: populateProviderToVersion(map[string]uint16{
 				providers.Cyberghost: 1,
 			}),
-			errMessage: "cannot decode servers for provider Cyberghost: " +
+			errMessage: "decoding servers for provider Cyberghost: " +
 				"json: cannot unmarshal string into Go struct field Servers.servers of type []models.Server",
 		},
 		"absent provider keys": {

internal/storage/servers.go

@@ -28,7 +28,7 @@ func (s *Storage) SetServers(provider string, servers []models.Server) (err erro
 
 	err = s.flushToFile(s.filepath)
 	if err != nil {
-		return fmt.Errorf("cannot save servers to file: %w", err)
+		return fmt.Errorf("saving servers to file: %w", err)
 	}
 	return nil
 }

internal/storage/sync.go

@@ -23,7 +23,7 @@ func (s *Storage) syncServers() (err error) {
 
 	serversOnFile, err := s.readFromFile(s.filepath, hardcodedVersions)
 	if err != nil {
-		return fmt.Errorf("cannot read servers from file: %w", err)
+		return fmt.Errorf("reading servers from file: %w", err)
 	}
 
 	hardcodedCount := countServers(s.hardcodedServers)
@@ -52,7 +52,7 @@ func (s *Storage) syncServers() (err error) {
 
 	err = s.flushToFile(s.filepath)
 	if err != nil {
-		return fmt.Errorf("cannot write servers to file: %w", err)
+		return fmt.Errorf("writing servers to file: %w", err)
 	}
 	return nil
 }