BUG: Tux can get stuck in a wall when an egg is collected

[onpon4]

SuperTux Classic version: 0.4.0 System information: Linux (Debian 11)

Describe the bug If you collect the egg powerup (while small) and as a result of getting bigger, you end up inside of a wall, you get permanently stuck.

To Reproduce Steps to reproduce the behavior:

1. Enter the Togble Road level as small Tux.
2. Hit the block which spawns an egg from the left side (so that it moves to the right).
3. Quickly move into the small gap to the right, then stand there and wait for the snowball to come to you.
4. Tux will get big, and he will be stuck on the jumping animation. (See screenshot above.)

Expected behavior There are a couple potential approaches to prevent this from happening. The one that most closely matches Milestone 1 of SuperTux would be to simply slowly eject Tux down if there's no solid tile beneath him, or otherwise eject him in the direction that he's facing. He could also be ejected in a manner more similar to the Mario games. Alternatively, the modern SuperTux route of causing Tux to get damaged when he's stuck in a wall could be used.