check spriteColorId with typeof instead of truthy

This allows for spriteColorId === 0.

Author: towerofnix

src/Renderer.ts

@@ -489,7 +489,7 @@ export default class Renderer {
     // Used for mapping drawn sprites back to their indices in a list.
     // By looking at the color of a given pixel, we can tell which sprite is
     // the topmost one drawn on that pixel.
-    if (drawMode === ShaderManager.DrawModes.SPRITE_ID && spriteColorId) {
+    if (drawMode === ShaderManager.DrawModes.SPRITE_ID && typeof spriteColorId === "number") {
       this.gl.uniform3fv(shader.uniforms.u_spriteId, idToColor(spriteColorId));
     }