Looks like java can't find the files and or couldn't load them, so for me could either be an overflow(so you don't have enough memory/too many programs opened) or something like doesn't have all the files out of the .rar , or to check the java control panel and manually check for updates because the pixmap error was a random bug i had for one other game last month and i solved it like that, ill add something if i find something else but no promise
Edit i also used a 2018 downgraded version of it and worked super fine cuz this game its fairly stable, so pick your poison i guess