keycloak/js/libs/ui-shared/src/utils/errors.ts

import { NetworkError } from "@keycloak/keycloak-admin-client";

const ERROR_FIELDS = ["error", "errorMessage"];
const ERROR_DESCRIPTION_FIELD = "error_description";

export function getErrorMessage(error: unknown) {
  if (typeof error === "string") {
    return error;
  }

  if (error instanceof NetworkError) {
    return getNetworkErrorMessage(error.responseData);
  }

  if (error instanceof Error) {
    return error.message;
  }

  throw new Error("Unable to determine error message.");
}

export function getErrorDescription(error: unknown) {
  if (!(error instanceof NetworkError)) {
    return;
  }

  const data = error.responseData;

  return getNetworkErrorDescription(data);
}

export function getNetworkErrorDescription(data: unknown) {
  if (
    typeof data === "object" &&
    data !== null &&
    ERROR_DESCRIPTION_FIELD in data &&
    typeof data[ERROR_DESCRIPTION_FIELD] === "string"
  ) {
    return data[ERROR_DESCRIPTION_FIELD];
  }
}

export function getNetworkErrorMessage(data: unknown) {
  if (typeof data !== "object" || data === null) {
    return;
  }

  for (const key of ERROR_FIELDS) {
    const value = (data as Record<string, unknown>)[key];

    if (typeof value === "string") {
      return value;
    }
  }
}