Error Handling Guide

# Error Handling Guide for Google Antigravity

Master error handling in Google Antigravity IDE.

## Custom Error Types

```typescript
export class AppError extends Error {
  constructor(
    message: string,
    public code: string,
    public statusCode: number = 500
  ) {
    super(message);
    this.name = this.constructor.name;
  }
}

export class ValidationError extends AppError {
  constructor(message: string, public fields: Record<string, string[]>) {
    super(message, "VALIDATION_ERROR", 400);
  }
}

export class NotFoundError extends AppError {
  constructor(resource: string, id: string) {
    super(`${resource} with id ${id} not found`, "NOT_FOUND", 404);
  }
}
```

## Result Type Pattern

```typescript
type Result<T, E = Error> =
  | { success: true; data: T }
  | { success: false; error: E };

function ok<T>(data: T): Result<T, never> {
  return { success: true, data };
}

function err<E>(error: E): Result<never, E> {
  return { success: false, error };
}

async function getUser(id: string): Promise<Result<User, AppError>> {
  const user = await db.user.findUnique({ where: { id } });
  if (!user) return err(new NotFoundError("User", id));
  return ok(user);
}
```

## Best Practices

1. **Use custom error types**
2. **Result types for explicit handling**

Google Antigravity IDE provides error handling scaffolding.