**System Information**
Operating system: win10
**Blender Version**
Broken: (2.90.2 Alpha, 2.79b)
**Short description of error**
Curve has 2 beveled splines, one is zero length (see it in edit mode), end is trimmed at 0.99 value with "spline" mode (see curve's data tab).
Enabling subsurf modifier in viewport crashes Blender. Other trimming modes works w/o issue.
**Exact steps for others to reproduce the error**
Open file,- In an empty scene, add the biezer curve
- Go to Edit mode
- Duplicate and move the spline ({key Shift D})
- Set handle type of the new spline to `free` ({key V})
- Scale this new spline to zero ({key S 0})
- Exit edit mode
- In `Object Data Properties` -> `Geometry` -> `Bevel` set:
- `Depth`: 1.0
- `Bevel End`: 0.99
- `Bevel Mapping Start`: Spline
- `Bevel Mapping End`: Spline
- Add the subsurf modifier -> crash
or:
- Open attached file
- enable subsurf modifier in viewport -> crash
{F8716817}