Follow up from https://github.com/facebook/react/pull/11616.

Here's one I found. These two invariants:

https://github.com/facebook/react/blob/7e7127387ba64f57299eaff8656542cea6fb3a2d/packages/react-reconciler/src/ReactFiberClassComponent.js#L330-L343

are in a function that's behind a DEV block:

https://github.com/facebook/react/blob/7e7127387ba64f57299eaff8656542cea6fb3a2d/packages/react-reconciler/src/ReactFiberClassComponent.js#L447-L449

I don't think this is intentional, but need to verify.

There may be more. I'll use this issue to track while https://github.com/facebook/react/pull/11616 preserves existing behavior.
return renderIntoDom(element, div, false, errorCount);
};
const clientRenderOnServerString = async (element, errorCount = 0) => {
  const markup = await renderIntoString(element, errorCount);
  resetModules();
  var domElement = document.createElement('div');
  domElement.innerHTML = markup;
  let serverNode = domElement.firstChild;
  const firstClientNode = await renderIntoDom(
    element,
    domElement,
    true,
    errorCount,
  );
  let clientNode = firstClientNode;
  
  while (serverNode || clientNode) {
    expect(serverNode != null).toBe(true);
    expect(clientNode != null).toBe(true);
    expect(clientNode.nodeType).toBe(serverNode.nodeType);
    
    
    
    expect(serverNode === clientNode).toBe(true);
    serverNode = serverNode.nextSibling;
    clientNode = clientNode.nextSibling;
  }
  return firstClientNode;
};
function BadMarkupExpected() {}