Computing leaf hashes should be done after the range check

[andrijamitrovic23]

computeLeafHashesIfNecessary should be done after the range check. This calculation could be time/resource consuming but unnecessarily called if the range is invalid.

[andrijamitrovic23]

Similar type of issue to Hasher initialization and reset should be done after validity checks.

[staheri14]

A relevant issue #108

[staheri14]

Thanks for opening the issue, your point is right about the computation overhead, however, in this case, the computeLeafHashesIfNecessary should not be moved as it affects the length of the leafHashes which is used in earlier lines.