In the current launcher in classic to infdev, all versions just crash when trying to load the assets. This is in the game. The versions that have this glitch are inf-20100618, c0.30_01c, c0.0.13a, c0.0.13a_03, and c0.0.11a. I don't know why this happens but I think it's a bug when loading minecraft. (Note: This is for the versions that I listed above not 1.16.5!)