fix(derive_key_from_path): check length of current_key_material

[DeckerSU]

The derive_key_from_path function:

https://github.com/KomodoPlatform/komodo-defi-framework/blob/a7ffbb1858db794abe7929fd4dea90840bed292f/mm2src/crypto/src/key_derivation.rs#L135-L152

could potentially lead to a panic if the master_node length is not 64.

For example, calling it like this:

let master_node = [0u8; 32];
let result = derive_key_from_path(&master_node, "");

In this case, since the loop over path will not be executed, current_key_material remains unchanged, and attempting to slice current_key_material[32..64] will cause a panic.

Another potential panic occurs when attempting to slice current_key_material[..32] if master_node has a length below 32.

Possible Solution

A simple fix for both cases is to check the length before proceeding:

if current_key_material.len() < 64 {
    return MmError::err(KeyDerivationError::InvalidKeyLength);
}

This would prevent panics and ensure safer execution.