getTreeNameFromConstructorFn does not work for registered trees

[rootulp]

Context

#277 introduced a breaking change that requires users of this library to register trees via RegisterTree. Trees are later fetched from a global map of trees based on their treeConstructor (a.k.a. treeCreatorFn).

Problem

This line does not evaluate to true when I expect it to.

rsmt2d/tree.go

Line 77 in bb5e119

if reflect.DeepEqual(reflect.ValueOf(treeFn), reflect.ValueOf(treeConstructor)) {

For example, in celestiaorg/celestia-app#3065 I'm registering a tree for the square size 1. Then I run TestMinDataAvailabilityHeader which fails because the pointer inside treeFn doesn't match the pointer inside treeConstructor.

Screenshot

Proposal

1. Revert fix!: UnmarshalJSON is limited to the default Tree bug #277
2. Explore refactor! Change ComputeExtendedDataSquare argument from TreeConstructorFn to string #278