Dynamic Errors not handled in Box of Errors for Function Results

[sachindkagrawal15]

When we use Box on function returning a result, the underlying error type is only known at runtime and not statically known.

There are instances in code where Box is used but there is no handling of dynamic errors in the function

Examples:

1. zk_prover/src/merkle_sum_tree/tree.js
   Function get_leaf_node_hash_preimage
2. zk_prover/src/merkle_sum_tree/utils/build_tree.rs
   Function build_merkle_tree_from_leaves
3. zk_prover/src/merkle_sum_tree/mst.rs
   Function from_params
4. backend/src/apis/round.rs
   Function new