Steps to reproduce:

1. Add a mesh.
2. Add another bone, so the hierarchy looks like this:
   

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3. Bind both bones to the mesh.
4. Edit the mesh vertices a little.
5. Reset the mesh, so the "remove weights" warning comes up. Remove the weights.
6. Weights will still be in the Bones list when you click the mesh. Hilight both in the list and click Remove at the bottom and it crashes.

Hope that about covers it!