Fix recursive batch() use

src/batch.luau

@@ -11,13 +11,15 @@ local function batch(setter: () -> ())
 
     local ok, err: string? = pcall(setter)
 
-    flags.batch = false
-    
-    if not ok then throw(`error occured while batching updates: {err}`) end
-
-    if not already_batching then -- todo: flush anyways?
-        graph.flush_update_queue()
+    if not already_batching then
+        flags.batch = false
+        
+        if not already_batching then
+            graph.flush_update_queue()
+        end
     end
+
+    if not ok then throw(`error occured while batching updates: {err}`) end
 end
 
 return batch

src/graph.luau

@@ -185,8 +185,11 @@ local function queue_children<T>(node: StartNode<T>)
     update_queue.n = i
 end
 
+local _flushing = false
 local function flush_update_queue()
-    -- todo: test with recursive batch sets
+    assert(not flushing, "recursive queue flush occured") -- todo
+    _flushing = true
+
     local n0 = 0
 
     local i = n0 + 1
@@ -203,6 +206,8 @@ local function flush_update_queue()
     end
 
     update_queue.n = n0
+
+    _flushing = false
 end
 
 local function update<T>(root: StartNode<T>)