Mobs do not get pushed out of blocks + Spider has wrong damagebox

For example, if you spawn a Spider on the following block setting, you'll notice that 1. the spider will receive damage, and 2. that it doesn't get pushed out of it (while that shouldn't be needed anyway as it shouldn't get damage there in the first place):

X = block
Y = empty
O = empty + spawnplace for normal Spider

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