Slicing fails when perimeter is twice as wide as external perimeter, but only one perimeter is specified

[dougisfunny]

Description of the bug

If you set extrusion width to be twice (or more) for the perimeter compared to the external perimeter and then set it to only have one perimeter the slicing fails.

This only happens in arachne.

Expected:

Unexpected:

Setting it to vase mode makes it appear to fail differently in that it essentially chooses to skip a few of the bottom most layers.

Project file & How to reproduce

1. Open any version of PrusaSlicer with arachne.
2. Set it to one of the built in presets for printer filament and print settings (or use a custom one if you so choose)
3. Change the perimeter extrusion width to double the external perimeter extrusion width. So if you are using a .4 nozzle and print external perimeters to .42, set the perimeters value to .84 for example.
4. Set the number of perimeters to 1.
5. Load a model of your choosing, I often just right click to add shape-> box, cylinder, or whatever you choose.
6. Slice.
   Shape-Cylinder.zip

Checklist of files included above

• Project file
• Screenshot

Version of PrusaSlicer

2.7.0-alpha1, but also every version that I have tried with arachne.

Operating system

Windows 10

Printer model

Prusa XL, Prusa i3 Mk3s

[lukasmatena]

Reproduced, thanks.
arachne_perimeters.zip

[lukasmatena]

Actually, I am closing this as a duplicate of #11082.