Get into 4 iframes one by one

I have 4 iframes and I need to fill an input in them one by one.

This is my code:

const elementHandleNum = await page.$(OrderDetails.iframeNumber);
const frameNum = await elementHandleNum.contentFrame();
await frameNum.waitForSelector(OrderDetails.cardNumberInput);
await frameNum.type(OrderDetails.cardNumberInput, OrderDetails.cardNumber);

const elementHandleName = await page.$(OrderDetails.iframeName);
const frameName = await elementHandleName.contentFrame();
await frameName.waitForSelector(OrderDetails.cardNameInput);
await frameName.type(OrderDetails.cardNameInput, OrderDetails.cardName);

const elementHandleDate = await page.$(OrderDetails.iframeExDate);
const frameDate = await elementHandleDate.contentFrame();
await frameDate.waitForSelector(OrderDetails.exDateInput);
await frameDate.type(OrderDetails.exDateInput, OrderDetails.exDate);

const elementHandleSec = await page.$(OrderDetails.iframeSecCode);
const frameSec = await elementHandleSec.contentFrame();
await frameSec.waitForSelector(OrderDetails.secCodeInput);
await frameSec.type(OrderDetails.secCodeInput, OrderDetails.secCode);

and the error is after the first iframe

TypeError: Cannot read property 'contentFrame' of null

How to get into the second iframe?