fix empty grid

d2layouts/d2layouts.go

@@ -67,8 +67,12 @@ func LayoutNested(ctx context.Context, g *d2graph.Graph, graphInfo GraphInfo, co
 			for _, e := range nestedGraph.Edges {
 				e.Move(dx, dy)
 			}
-
 		} else if !gi.isDefault() {
+			// empty grid can have 0 objects..
+			if gi.DiagramType == GridDiagram && !gi.IsConstantNear && len(curr.Children) == 0 {
+				continue
+			}
+
 			extractedInfo[curr] = gi
 
 			// There is a nested diagram here, so extract its contents and process in the same way