Merge pull request #2309 from Eulenmensch93/fix_2291_unexpected_spr_r…

…endering_with_undefined_colorkey

Fix issue 2291

src/api/js.c

@@ -237,7 +237,7 @@ static JSValue js_spr(JSContext *ctx, JSValueConst this_val, s32 argc, JSValueCo
     }
     else
     {
-        colors[0] = getInteger2(ctx, argv[3], 0);
+        colors[0] = getInteger2(ctx, argv[3], -1);
         count = 1;
     }