Fix crash on degenerate curves

Author: wtholliday

Sources/vger/vger.mm

@@ -264,6 +264,11 @@ void vgerStrokeBezier(vgerContext vg, vgerBezierSegment s, float width, vgerPain
     float2 d1 = rot90 * width * normalize(s.c - s.a);
     float2 d2 = rot90 * width * normalize(s.c - s.b);
 
+    // Don't render degenerate curves.
+    if (any(isnan(d0)) || any(isnan(d1)) || any(isnan(d2))) {
+        return;
+    }
+
     vgerMoveTo(vg, s.a - d0);
     vgerQuadTo(vg, s.b - d1, s.c - d2);
     vgerLineTo(vg, s.c + d2);

Tests/vgerTests/vgerTests.mm

@@ -136,6 +136,7 @@ - (void) testBasic {
 
     vgerFillCircle(vg, float2{256, 256}, 40, cyan);
     vgerStrokeBezier(vg, {{256,256}, {256,384}, {384,384}}, 1, white);
+    vgerStrokeBezier(vg, {{384,384}, {512,512}, {512,512}}, 1, white); // Degenerate
     vgerFillRect(vg, float2{400,100}, float2{450,150}, 10, vgerLinearGradient(vg, float2{400,100}, float2{450, 150}, float4{0,1,1,1}, float4{1,0,1,1}, 0));
     vgerFillRect(vg, float2{400,200}, float2{450,250}, 10, vgerRadialGradient(vg, float2{425,225}, 10, 40, float4{0,1,1,1}, float4{1,0,1,1}, 0));
     vgerStrokeArc(vg, float2{100,400}, 30, 3, theta, ap, white);