Hi Tobias,
I'm almost sure the error Uncaught TypeError: Cannot read property 'render' of undefined is thrown because you have used 'plain HTML' in your HTML fragment:
<p>Hello World</p>
the moment you put in something UI5-specific, for instance:
<p>Hello World</p>
<div data-sap-ui-type="sap.ui.commons.Button" id="Button2" data-text="Hello World Button"></div>
then it should execute properly (however, the 'plain HTML' content seems to be ignored, see this example using your code)
I have almost no experience with HTML views/fragments so I can't really comment on the reason why this happens...