Extract API error logic to helper

cmd/cmd.go

@@ -1,7 +1,9 @@
 package cmd
 
 import (
+	"encoding/json"
 	"fmt"
+	"net/http"
 
 	"io"
 
@@ -70,3 +72,21 @@ func validateUserConfig(cfg *viper.Viper) error {
 	}
 	return nil
 }
+
+// decodedAPIError decodes and returns the error message from the API response.
+// If the message is blank, it returns a fallback message with the status code.
+func decodedAPIError(resp *http.Response) error {
+	var apiError struct {
+		Error struct {
+			Type    string `json:"type"`
+			Message string `json:"message"`
+		} `json:"error,omitempty"`
+	}
+	if err := json.NewDecoder(resp.Body).Decode(&apiError); err != nil {
+		return fmt.Errorf("failed to parse API error response: %s", err)
+	}
+	if apiError.Error.Message != "" {
+		return fmt.Errorf(apiError.Error.Message)
+	}
+	return fmt.Errorf("unexpected API response: %d", resp.StatusCode)
+}

cmd/submit.go

@@ -2,7 +2,6 @@ package cmd
 
 import (
 	"bytes"
-	"encoding/json"
 	"errors"
 	"fmt"
 	"io"
@@ -254,12 +253,7 @@ func (s *submitCmdContext) submit(metadata *workspace.ExerciseMetadata, docs []w
 	defer resp.Body.Close()
 
 	if resp.StatusCode == http.StatusBadRequest {
-		var jsonErrBody apiErrorMessage
-		if err := json.NewDecoder(resp.Body).Decode(&jsonErrBody); err != nil {
-			return fmt.Errorf("failed to parse error response - %s", err)
-		}
-
-		return fmt.Errorf(jsonErrBody.Error.Message)
+		return decodedAPIError(resp)
 	}
 
 	bb := &bytes.Buffer{}
@@ -430,10 +424,3 @@ func (s submitValidator) isRequestor(metadata *workspace.ExerciseMetadata) error
 func init() {
 	RootCmd.AddCommand(submitCmd)
 }
-
-type apiErrorMessage struct {
-	Error struct {
-		Type    string `json:"type"`
-		Message string `json:"message"`
-	} `json:"error,omitempty"`
-}