[Bug] Solver panics on the start of the simulation

Summary

The solver crashes at the beginning of the simulation when I am trying to inflate an airbag mesh. The scene only contained one shell geometry which is the airbag mesh itself with no other solid or shell or rods.

Here is the screenshot:

Steps to Reproduce

1. Build a scene with a complex quad formation
2. Create a shell dynamic group
3. Tick inflate and set a desirable pressure
4. Transfer and run simulation

Expected Behavior

The simulation runs as usual

Actual Behavior

[2026-06-03 11:49:09] thread 'main' (27012) panicked at crates\ppf-cts-solver\src\mesh.rs:160:9:
[2026-06-03 11:49:09] assertion failed: keys.insert(e)

Environment

OS : Windows 11
Model : HP ZBook Fury
Blender : 5+
Solver version : c51dd0d

Contribution Agreement

• I confirm that any code, patches, scripts, attachments, or other copyrightable material I include in this issue may be used, reproduced, modified, and distributed by this project under the Apache License 2.0 or as otherwise described in CONTRIBUTING.md.
• This is a bug report from the community (please provide a reference below).

Community Reference

No response

Start at crates/ppf-cts-solver/src/mesh.rs:160, where the assertion failure is reported, and reproduce the Blender scene with one inflated shell mesh. Compare the mesh input and solver state at the start of the simulation; done means the reported scene no longer panics and the simulation runs as expected.