LibGfx: Only attempt to paint strokes with a width > 0

Author: https://github.com/MacDue
Commit: a9b4e876d0
Pull-request: https://github.com/SerenityOS/serenity/pull/20053

Userland/Libraries/LibGfx/Path.cpp

@@ -416,6 +416,8 @@ Path Path::stroke_to_fill(float thickness) const
     // Note: This convolves a polygon with the path using the algorithm described
     // in https://keithp.com/~keithp/talks/cairo2003.pdf (3.1 Stroking Splines via Convolution)
 
+    VERIFY(thickness > 0);
+
     auto& lines = split_lines();
     if (lines.is_empty())
         return Path {};