mappingConfig fails to pull

[indig0fox]

This call was intermittently failing for me and causing the playback page to get stuck on "Loading" the replay

R3-Web/dist/playback.php

Lines 27 to 32 in ac92ae0

	$url = 'https://r3tiles-a.titanmods.xyz/config.json';
	$ch = curl_init();
	curl_setopt($ch, CURLOPT_URL, $url);
	curl_setopt($ch, CURLOPT_RETURNTRANSFER,1);
	$mappingConfig = curl_exec($ch);
	curl_close($ch);

So I had to add a null check in playback.php

if (!$mappingConfig)
	$mappingConfig = '{}';