Merge reactive scope refactor

src/untrack.luau

@@ -1,20 +1,27 @@
 if not game then script = require "test/relative-string" end
 
+local throw = require(script.Parent.throw)
 local graph = require(script.Parent.graph)
 type Node<T> = graph.Node<T>
-local refs = graph.refs
+local get_scope = graph.get_scope
 
 local function untrack<T>(source: () -> T): T
-    local initial = #refs
+    local scope = get_scope()
+    if not scope then
+        throw("cannot untrack in non-reactive scope")
+    end; assert(scope)
 
-    local value = source()
+    -- sources are only tracked if the node in scope has an effect
+    local effect = scope.effect
+    scope.effect = false
 
-    -- remove any references made since `untrack()` was called
-    for i = initial, #refs do
-        refs[i] = nil
-    end
+    local ok, result = pcall(source)
 
-    return value
+    scope.effect = effect :: () -> ()
+
+    if not ok then error(result, 0) end
+
+    return result
 end
 
 return untrack