graphql/jsutils/invariant.js.flow

A Query Language and Runtime which can target any service.

// @flow strict
export default function invariant(condition: mixed, message?: string): void {
  const booleanCondition = Boolean(condition);
  // istanbul ignore else (See transformation done in './resources/inlineInvariant.js')
  if (!booleanCondition) {
    throw new Error(
      message != null ? message : 'Unexpected invariant triggered.',
    );
  }
}