error-handling-patterns

name	Error Handling Patterns
description	Standardized error responses to replace generic 500s with useful JSON
version	1.0.0

Skill: Error Handling Patterns

Use this skill to implement structured error handling across the Wix-GAS Bridge.

1. The Standard Error Response (GAS)

Stop throwing raw text. Always return this JSON object from GAS doPost() catches:

return ContentService.createTextOutput(JSON.stringify({
    success: false,
    error: {
        code: "ERROR_CODE_ENUM",
        message: "Human readable message for logging",
        userMessage: "Friendly message for UI",
        retryable: true|false
    }
})).setMimeType(ContentService.MimeType.JSON);

2. Standard Error Codes

Code	Meaning	User Message	Retry?
AUTH_FAIL	API Key Invalid	"Access Denied. Contact Support."	No
SCHEMA_MISMATCH	Missing fields	"Form Error. Please refresh."	No
SIGNNOW_API_FAIL	SignNow is down	"Document Service Busy. Retrying..."	Yes
LOCK_TIMEOUT	Simultaneous edits	"System Busy. Please submit again."	Yes
DRIVE_QUOTA	Google Drive full	"Storage Error. Call Dispatch."	No

3. Frontend Implementation (Velo)

When parsing the GAS response in gasIntegration.jsw:

// backend/gasIntegration.jsw
if (!result.success) {
    console.error(`GAS Error [${result.error.code}]: ${result.error.message}`);
    
    // Throw standard error for UI to catch
    throw new Error(result.error.userMessage || "System Error");
}

4. UI Implementation (Page Code)

In portal-indemnitor.js's catch block:

catch (error) {
    // Show the user-friendly message from the backend
    showError(error.message); 
    
    // If "System Busy", auto-retry logic could go here
}