errors.md

paths	scripts/**/*.ts

Error Handling Rules

All expected failures use the Result<T, E> tuple type. Never throw exceptions. See the full standard: Error Handling.

Result Type

type Result<T, E = Error> = readonly [E, null] | readonly [null, T];

• Success: [null, value]
• Failure: [error, null]

Conventions

• Define domain-specific error interfaces with a descriptive type or reason field
• Create type aliases for domain results (e.g., type ConfigResult<T> = Result<T, ConfigError>)
• Wrap async operations that can reject with a try/catch that returns a Result tuple

Chaining with Early Returns

const [configError, config] = loadConfig(workspace);
if (configError) return [configError, null];

const [resolveError, result] = resolve(config, name);
if (resolveError) return [resolveError, null];

return [null, result];

Error Type Pattern

interface ConfigError {
  readonly type: "invalid_json" | "missing_field" | "unknown_key";
  readonly message: string;
}

Rules

• Never throw inside a function that returns Result
• Always check the error element before accessing the value
• Use ts-pattern match for exhaustive handling of multiple error variants
• Map low-level errors to domain-specific error reasons