improvements

scripts/graphics.cm

@@ -312,7 +312,7 @@ graphics.texture = function texture(path) {
   if (!cache[id]) {
     var ipath = res.find_image(id)
     if (!ipath)
-      throw new Error(`unknown image ${id}`)
+      return graphics.texture('notex')
     
     var result = create_image(ipath)
     cache[id] = result