Fill by line art detection produces Segmentation fault with some images
The issue is in the function gimp_lineart_curvature_extremums :
max_curvature_pixel is initialized with gimp_vector2_new (-1.0, -1.0) and max_curvature to 0.0
If all tested curvature values are zero, the point (-1.0, -1.0) is added to the max_positions array.
Later, these negative values are used to compute array offset, causing segmentation fault.
master and gimp-2-10 branches are affected.