When using Poseidon hash, different bytearray-keys can lead to same values in the tree

[arnaucube]

example:
0x0100 interpreted in little-endian bigint is 1, 0x01000000 interpreted in little-endian bigint is 1 (same would happen in big-endian with 0x0001 and 0x00000001).

This affects when adding & updating & getting leafs from the tree, and also when checking merkle-proofs.

One option could be that if the tree uses Poseidon as hashFunc, force the input keys to be of 32 bytes (32-byte little-endian representation of a bigint).