Reproduce a bug example, (Model disappeared when same 3 models pathtraced)

[dongho-shin]

related : #668

2024-08-12.3.50.16-1.mov

how to reproduce a bug

1. check enable
2. uncheck enable
3. check add model
4. check enable

[dongho-shin]

Sorry for long time to fix this @gkjohnson ,
Actually this issue was caused by MeshBVHUniformStruct.js in three-mesh-bvh, wrong length comparison

cachedIndexAttr is still being used as an index attribute, but the
indirectBuffer is a Buffer for reference
It is 1/3 the size of the geometry index count because of that part below

So the first time it's cached, the simple box's case calls
count(undefined)
length(1) ← default dummy data before adding any boxes at all, which is subsequently deleted.
Add 1 box
→ count(3) length(12 box 1 index data)
Add 2 additional boxes after the string
→ count(36) length(36 box 2 boxes added to match)
So the index length was not growing properly, so the data addition was not working properly.

After the caching comparison, the following logic

Because of adding by indirectBuffer, the properly cached IndexAttr was not tripled accordingly, so the data was not added.