diff --git a/src/collision/GridBroadphase.hx b/src/collision/GridBroadphase.hx
index 4342b9f9..7c91b64a 100644
--- a/src/collision/GridBroadphase.hx
+++ b/src/collision/GridBroadphase.hx
@@ -246,7 +246,11 @@ class GridBroadphase {
 		for (i in xStart...xEnd) {
 			for (j in yStart...yEnd) {
 				for (surfIdx in cells[16 * i + j]) {
-					var surf = objects[surfIdx].object;
+					// remove() nulls the slot but keeps the index; build() skips these too.
+					var proxy = objects[surfIdx];
+					if (proxy == null)
+						continue;
+					var surf = proxy.object;
 					if (surf.key == searchKey)
 						continue;
 					surf.key = searchKey;
diff --git a/src/gui/PlayGui.hx b/src/gui/PlayGui.hx
index 17ced146..b57ffbed 100644
--- a/src/gui/PlayGui.hx
+++ b/src/gui/PlayGui.hx
@@ -1077,7 +1077,8 @@ class PlayGui {
 		gemCountNumbers[4].anim.visible = false;
 		gemCountNumbers[5].anim.visible = false;
 
-		var off = playerList[0].us ? 10 : 0;
+		// playerList is multiplayer-only, so it is empty in single player.
+		var off = (playerList.length > 0 && playerList[0].us) ? 10 : 0;
 
 		gemCountNumbers[0].anim.currentFrame = off + collectedHundredths;
 		gemCountNumbers[1].anim.currentFrame = off + collectedTenths;