chore: guard centroid() against empty polygon (session close)

062b60715bd0abcad43b8615480f2a970a0b088b · 2026-07-24 23:45:23 -0700 · Steve

Defensive n===0 guard so centroid never emits NaN into gradient/arc math.
Both lint + refactor review passes otherwise found the code clean.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Files touched

M index.html

Diff

commit 062b60715bd0abcad43b8615480f2a970a0b088b
Author: Steve <steve@designerwallcoverings.com>
Date:   Fri Jul 24 23:45:23 2026 -0700

    chore: guard centroid() against empty polygon (session close)
    
    Defensive n===0 guard so centroid never emits NaN into gradient/arc math.
    Both lint + refactor review passes otherwise found the code clean.
    
    Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
---
 index.html | 1 +
 1 file changed, 1 insertion(+)

diff --git a/index.html b/index.html
index fbbfc7e..a32f9f2 100644
--- a/index.html
+++ b/index.html
@@ -394,6 +394,7 @@
 
   function centroid(poly) {
     var a = 0, cx = 0, cy = 0, n = poly.length;
+    if (n === 0) return [W / 2, H / 2]; // guard: never emit NaN from an empty poly
     for (var i = 0; i < n; i++) {
       var j = (i + 1) % n;
       var x0 = poly[i][0], y0 = poly[i][1];

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