function requireFirstRequestIdempotencyKey(requestMock: {

mock: { calls: ReadonlyArray<ReadonlyArray<unknown>> };

}): string {

const firstCall = requestMock.mock.calls.at(0);

const firstCall = requestMock.mock.calls[0];

if (!firstCall) {

throw new Error("expected request mock call");

}

const params = firstCall.at(1);

const params = firstCall[1];

if (!params || typeof params !== "object") {

throw new Error("expected request params");

}