guard.ts

type GuardedResult<ReturnType, DefaultValueType = ReturnType> = ReturnType | DefaultValueType;
type GuardedFn<ReturnType, DefaultValueType = ReturnType> = (
  ...args
) => GuardedResult<ReturnType, DefaultValueType>;

function guard<ReturnType, DefaultValueType = ReturnType>(
  fn: GuardedFn<ReturnType, DefaultValueType>,
  defaultValue: GuardedResult<ReturnType, DefaultValueType>
) {
  const guarded: GuardedFn<ReturnType, DefaultValueType> = (...args) => {
    try {
      return fn(...args);
    } catch (error) {
      return handleError(error, defaultValue);
    }
  };

  return guarded;
}

function guardAsync<ReturnType, DefaultValueType = ReturnType>(
  fn: GuardedFn<Promise<ReturnType | DefaultValueType>>,
  defaultValue: GuardedResult<Promise<ReturnType | DefaultValueType>>
) {
  return guard<Promise<ReturnType | DefaultValueType>>(
    (...args) =>
      fn(...args).then(x => x, error => handleError(error, defaultValue)),
    defaultValue
  );
}

function handleError<T>(error: Error, defaultValue: T): T {
  if (isProductionBuild) {
    Sentry.captureException(error);
  } else {
    handleDevelopmentError(error);
  }
  return defaultValue;
}