test: failing test for imt tree root

[alrevuelta]

Description

This PR adds a failing test for the LazyIMT tree that would be expected to pass. When creating a tree with more than 128 elements inserted, when checking its root() the transaction reverts with the following error. With 128 it works, with 129 (and more) it fails. Note that in both cases, the depth of the tree is enough to fit all elements.

 Error: call revert exception; VM Exception while processing transaction: reverted with panic code 17 [ See: https://links.ethers.org/v5-errors-CALL_EXCEPTION ] (method="root()", data="0x4e487b710000000000000000000000000000000000000000000000000000000000000011", errorArgs=[{"type":"BigNumber","hex":"0x11"}], errorName="Panic", errorSignature="Panic(uint256)", reason=null, code=CALL_EXCEPTION, version=abi/5.7.0)

It this expected?

[alrevuelta]

Does anyone have some spare time to look into this?

[vimwitch]

Hi @alrevuelta, thanks for submitting this. I've opened a pr with a fix and it should be merged soon.