Error Handling & Logging Patterns

Build systems that are debuggable in production through structured logging and intentional error handling.

Error Hierarchy Design

Custom Exception Classes

class AppError(Exception):
    """Base error for the application."""
    def __init__(self, message: str, code: str = "INTERNAL_ERROR", status: int = 500):
        self.message = message
        self.code = code
        self.status = status
        super().__init__(message)

class NotFoundError(AppError):
    def __init__(self, entity: str, id: str):