02:18:41game If on Windows, make sure to provide all of the necessary dll's as specified in the twitchsdk README. Also, make sure to set the PATH environment variable to point to the directory containing the dll's.
<log4j:Event logger="bsu" timestamp="1518358721503" level="ERROR" thread="Client thread">
<log4j:Message><![CDATA[Couldn't initialize twitch stream]]></log4j:Message>
The Twitch integration was removed, so that error has nothing to do with the actual crash, see if you still get an issue on 1.12.2. If you do:
On your launcher, click "Launch options", and click the instance you are using. Then, click the small green arrow in the "Game directory" line. In the folder that opens, open the launcher_log file, and copy its content to http://paste.ubuntu.com. Click "Paste!", then share with us the link (the URL) that it takes you to.