The game crashed whilst mouseclicked event handler Error: java.lang.NoClassDefFoundError: mtr/data/SavedRailBase

• I open the Minecraft Launcher
• Press Play
• My singleplayer map doesn't work
• The game crashes
• It then comes up with ERROR Game Crashed and then the message... 
• The game crashed whilst mouseclicked event handler Error: java.lang.NoClassDefFoundError: mtr/data/SavedRailBase

 

• I don't know why I can only choose 24w37a, 1.21.1 or future updates for the affected version but I'm using fabric-loader-0.16.5-1.19.2 so I'm choosing 1.21.1 and just don't care about it