fix: 每天都在修outlive

samples/helloworld.ks

@@ -1,11 +1,10 @@
 
 //mod D:\code\rs\tst\target\debug\tstlib.dll> m;
 
-let a() {
-  try throw (299)
-  catch e {
-    :e
-  }
-}
 
-log(a())
+let a = 5;
+let f1() {
+  let a = 20;
+  :||:a // 相当于return (||return a)
+}
+log(f1()()) // 20

src/runtime/outlive.rs

@@ -85,11 +85,13 @@ pub fn decrease_scope_count(mut scope: Scope) {
 
   loop {
     let prev = scope.outlives.fetch_sub(1, Ordering::Relaxed);
+    let parent = scope.parent;
     if prev == 1 && scope.ended {
       // println!("{:02}: scope drop by func: {:p}",ln(), scope.ptr);
       unsafe{ std::ptr::drop_in_place(scope.ptr) }
+      scope.ptr = std::ptr::null_mut();
     }
-    if let Some(prt) = scope.parent {
+    if let Some(prt) = parent {
       scope = prt;
     }else {
       break;