Fix: bind sampler uniforms to a 1x1 transparent texture — null samplers broke shader linking, so no ghosts rendered

public/js/ghosts/loader.js

@@ -20,10 +20,20 @@ const objCache = new Map();
 const texLoader = new THREE.TextureLoader();
 const texCache = new Map();
 
+/* A sampler2D uniform must ALWAYS be bound to a real texture: leaving it null makes
+ * the shader program fail to link on many GPUs, which would break every untextured
+ * ghost. This 1x1 fully-transparent pixel is the safe no-op binding. */
+const EMPTY_TEX = (() => {
+  const t = new THREE.DataTexture(new Uint8Array([0, 0, 0, 0]), 1, 1, THREE.RGBAFormat);
+  t.needsUpdate = true;
+  return t;
+})();
+
 function loadTexture(url) {
   if (!url) return null;
   if (!texCache.has(url)) {
-    const t = texLoader.load(url);
+    const t = texLoader.load(url, undefined, undefined,
+      () => console.warn('texture failed to load:', url));   // keeps the ghost alive
     t.colorSpace = THREE.SRGBColorSpace;
     texCache.set(url, t);
   }
@@ -41,8 +51,8 @@ function gradientMaterial(top, bottom, opacity, faceTex, torsoTex, bands) {
       uMinY: { value: 0 },
       uMaxY: { value: 1 },
       uTime: { value: 0 },
-      faceMap: { value: faceTex || null },
+      faceMap: { value: faceTex || EMPTY_TEX },
-      torsoMap: { value: torsoTex || null },
+      torsoMap: { value: torsoTex || EMPTY_TEX },
       hasFace: { value: faceTex ? 1 : 0 },
       hasTorso: { value: torsoTex ? 1 : 0 },
       // [centreY, halfHeight, halfWidth] in normalized model space
@@ -136,7 +146,8 @@ function pickModel(manifest, ov) {
 
 export async function buildGhost(ghost, gradients, manifest, characters) {
   const ov = resolveOverrides(ghost, characters);
-  const grad = gradients[ghost.color] || gradients.Blue;
+  const grad = (gradients && (gradients[ghost.color] || gradients.Blue))
+    || { top: '#51eaf1', bottom: '#529eff' };   // survive a missing/!oddly-shaped gradient payload
   const top = ov.topColor || grad.top;
   const bottom = ov.bottomColor || grad.bottom;
   const opacity = ov.opacity != null ? Number(ov.opacity) : 0.92;