chore(all): review error wrappings

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

internal/provider/ivpn/connection_test.go

@@ -37,7 +37,7 @@ func Test_Provider_GetConnection(t *testing.T) {
 		"error": {
 			storageErr: errTest,
 			errWrapped: errTest,
-			errMessage: "cannot filter servers: test error",
+			errMessage: "filtering servers: test error",
 		},
 		"default OpenVPN TCP port": {
 			filteredServers: []models.Server{

internal/provider/ivpn/updater/api.go

@@ -53,11 +53,11 @@ func fetchAPI(ctx context.Context, client *http.Client) (
 	decoder := json.NewDecoder(response.Body)
 	if err := decoder.Decode(&data); err != nil {
 		_ = response.Body.Close()
-		return data, fmt.Errorf("failed unmarshaling response body: %w", err)
+		return data, fmt.Errorf("decoding response body: %w", err)
 	}
 
 	if err := response.Body.Close(); err != nil {
-		return data, fmt.Errorf("cannot close response body: %w", err)
+		return data, fmt.Errorf("closing response body: %w", err)
 	}
 
 	return data, nil

internal/provider/ivpn/updater/api_test.go

@@ -27,7 +27,7 @@ func Test_fetchAPI(t *testing.T) {
 		},
 		"nil body": {
 			responseStatus: http.StatusOK,
-			err:            errors.New("failed unmarshaling response body: EOF"),
+			err:            errors.New("decoding response body: EOF"),
 		},
 		"no server": {
 			responseStatus: http.StatusOK,

internal/provider/ivpn/updater/servers.go

@@ -14,7 +14,7 @@ func (u *Updater) FetchServers(ctx context.Context, minServers int) (
 	servers []models.Server, err error) {
 	data, err := fetchAPI(ctx, u.client)
 	if err != nil {
-		return nil, fmt.Errorf("failed fetching API: %w", err)
+		return nil, fmt.Errorf("fetching API: %w", err)
 	}
 
 	hosts := make(map[string]struct{}, len(data.Servers))

internal/provider/ivpn/updater/servers_test.go

@@ -47,7 +47,7 @@ func Test_Updater_GetServers(t *testing.T) {
 		"http response error": {
 			warnerBuilder:  func(ctrl *gomock.Controller) common.Warner { return nil },
 			responseStatus: http.StatusNoContent,
-			err:            errors.New("failed fetching API: HTTP status code not OK: 204 No Content"),
+			err:            errors.New("fetching API: HTTP status code not OK: 204 No Content"),
 		},
 		"resolve error": {
 			warnerBuilder: func(ctrl *gomock.Controller) common.Warner {