fix: JS reliability bugs (SonarCloud S1764, S9383, S4275)

- scriptui.js: replace the self-comparison NaN check (o.max === o.max) with
  the explicit Number.isNaN(o.max) (S1764).
- sw.js: mark the fire-and-forget cache.put() with void and a .catch() so the
  promise rejection is handled (S9383).
- prelude.js: return __err(...) from the activeCamera getter so every path
  yields a value (S4275); __err always throws, so behavior is unchanged.

apps/effectcraft-web/web/sw.js

@@ -38,7 +38,7 @@ self.addEventListener("fetch", (event) => {
       const hit = await cache.match(key, { ignoreSearch: req.mode === "navigate" });
       if (hit) return hit;
       const res = await fetch(req);
-      if (res.ok && res.type === "basic") cache.put(req, res.clone());
+      if (res.ok && res.type === "basic") void cache.put(req, res.clone()).catch(() => {});
       return res;
     })(),
   );

crates/expr/src/prelude.js

@@ -461,7 +461,7 @@ Comp.prototype = {
       var l = this.layer(i);
       if (l.__info[10] === 'Camera' && l.active) return l;
     }
-    __err('Composition "' + this.name + '" has no active camera');
+    return __err('Composition "' + this.name + '" has no active camera');
   },
   layer: function (a, rel) {
     if (a !== null && typeof a === 'object' && a.__isLayer) return this.layer(a.index + (rel || 0));

crates/script/src/scriptui.js

@@ -840,7 +840,7 @@ function __uiJson(c, inherited) {
     o.value = Number(c.value) || 0;
     o.min = Number(c.minvalue) || 0;
     o.max = Number(c.maxvalue);
-    if (!(o.max === o.max)) o.max = 100;
+    if (Number.isNaN(o.max)) o.max = 100;
   }
   if (c.items) {
     o.items = c.items.map(function (it) { return String(it.text); });