[BUG] Rewinside Fly doesn't work in **1.12.2-Forge (cross_version devbuild)**

[commandblock2]

Describe the bug Rewinside Fly doesn't work in 1.12.2-Forge (cross_version devbuild) which is not yet released. When using fly with rewinside mode, the player will fall as if fly was disabled. However, 1.8.9-Forge cross_version does not have this issue. Btw LiquidWalk vanilla/ncp mode now bounce up and down unlike 1.8.9 one. Idk if this is related Hypixel mode doesn't work as well, however, BoostHypixel works for some strange reason.

To Reproduce Steps to reproduce the behavior:

1. Enable fly with rewinside mode
2. Notice the player falls as usual

Additional information:

• OS: Gentoo GNU/Linux
• LiquidBounce Build Version b73 c784d84 (self built 1.12)
• Minecraft Version 1.12.2
• It seemed this is happening because of none of the Block s in BlockBBEvent is BlockAir. I never see air in event.block in BlockBBEvent .aka classProvider.isBlockAir(event.block) was never true Edit0: There is indeed BlockAir in the event, but very rare (randomly). Edit1: Most likely that BlockAir no longer has a blockBox Edit2: I guees the BlockAir in the event might be a block that is on the top of a fence