Article content is "undefined", can't play

[Lichtschalter-5000]

Sometimes (two times in like ten games now for me), I get this kind of scenario.
My opponent (we both clicked "Play against random opponent" and got matched) could use the site as usual.

Console output:

Failed to load resource: net::ERR_CONNECTION_RESET  (/wiki/Star%20Trek%20(film):1)
Uncaught TypeError: Illegal invocation (index.js:179)
    at Emitter.onReceivePaths (index.js:179)
    at Emitter.emit (index.js:2)
    at WebSocket.e.onmessage (index.js:5)