The screen is black and the Chrome console shows the error Cannot read properties of null reading handle with the call stack pointing to a function called set shader
This could be due to a missing shader.
Possible solution:
In Chrome dev tools make sure that pause on code exceptions is enabled.
Refresh the page.
Once the code pauses on this error, check the call stack a few functions back to find the name of the material which is missing the shader.
Next, in the Unity Playworks Plugin window check the Assets tab and uncheck the missing shader.