CoolingBuffer.cpp:533 Assertion `sm.length > 0' failed in vase mode with fuzzy skin enabled.

[themanyone]

Description of the bug

The assertion sm.length > 0 means that a G1/G2/G3 move inside a _EXTRUDE_SET_SPEED block has zero length. This can happen
when "fuzzy skin" is enabled in vase mode, as the perimeter generator might generate zero-length segments. The fix is to
ignore zero-length segments when accumulating length for a speed modifier.

Project file & How to reproduce

1. Start prusa-slicer alpha
2. Load a simple primitive such as "cylinder".
3. Enable vase mode and fuzzy skin
4. Slice

prusa-slicer: /home/k/Downloads/src/Prusa/src/libslic3r/GCode/CoolingBuffer.cpp:533: 
std::vector<Slic3r::PerExtruderAdjustments> Slic3r::CoolingBuffer::parse_layer_gcode(const std::string&, 
std::array<float, 5>&) const: Assertion `sm.length > 0' failed.

Aider bot suggested a patch to gracefully skip zero-length extrusions in cooling moves. Will follow up with a PR.

Checklist of files included above

• Project file
• Screenshot

Version of PrusaSlicer

2.9.9-alpha1 [git]

Operating system

Linux Fedora 41

Printer model

Geeetch A10T