@netlify/config/lib/error.js

Netlify config module

// We distinguish between errors thrown intentionally and uncaught exceptions
// (such as bugs) with a `customErrorInfo.type` property.
export const throwUserError = function (messageOrError, error) {
    const errorA = getError(messageOrError, error);
    errorA[CUSTOM_ERROR_KEY] = { type: USER_ERROR_TYPE };
    throw errorA;
};
// Can pass either `message`, `error` or `message, error`
const getError = function (messageOrError, error) {
    if (messageOrError instanceof Error) {
        return messageOrError;
    }
    if (error === undefined) {
        return new Error(messageOrError);
    }
    error.message = `${messageOrError}\n${error.message}`;
    return error;
};
export const isUserError = function (error) {
    return (canHaveErrorInfo(error) && error[CUSTOM_ERROR_KEY] !== undefined && error[CUSTOM_ERROR_KEY].type === USER_ERROR_TYPE);
};
// Exceptions that are not objects (including `Error` instances) cannot have an
// `CUSTOM_ERROR_KEY` property
const canHaveErrorInfo = function (error) {
    return error != null;
};
const CUSTOM_ERROR_KEY = 'customErrorInfo';
const USER_ERROR_TYPE = 'resolveConfig';