When the last leaf is added, it is not actually required to set _finalize to true. This only works if claimedSize % BLOCK_SIZE_BYTES == 0, as otherwise the input will not be padded and the following check will fail:
For the call to succeed, one must pass all but the last state commitment, which corresponds to the empty block which is added as padding at the end in the case _input % BLOCK_SIZE_BYTES == 0.
The LPP can still be finalized later by passing no input and the last state commitment.
