API reference / @evolu/common / Result / Err

Interface: Err<E>

Defined in: packages/common/src/Result.ts:397

An error Result.

The error property can be any type that describes the error. For normal domain logic, use a plain object. This allows us to structure errors with custom fields (e.g., { type: "MyError", code: 123 }). Messages for users belong to translations, not to error objects.

If you need a stack trace for debugging, use an Error instance or a custom error class to include additional metadata.

Examples

Domain logic error (plain object, recommended)

const failure = err({
  type: "ParseJsonError",
  code: 1001,
  input: "foo",
});

Debugging with stack trace (error instance)

const failure = err(new Error("Something went wrong"));

Custom error class

class MyCustomError extends Error {
  constructor(
    public code: number,
    public input: string,
  ) {
    super(`Error ${code} on input: ${input}`);
    this.name = "MyCustomError";
  }
}
const failure = err(new MyCustomError(404, "bad-input"));

Type Parameters

Properties