fix corner case in `ie8` (#4532)

fixes #4531

1 files changed, 5 insertions, 3 deletions

diff --git a/lib/scope.js b/lib/scope.js
index 689100cf..a241cc59 100644
--- a/lib/scope.js
+++ b/lib/scope.js
@@ -311,8 +311,9 @@ AST_Toplevel.DEFMETHOD("figure_out_scope", function(options) {
         }
         if (node instanceof AST_SymbolLambda) {
             var def = node.thedef;
-            redefine(node, node.scope.parent_scope.resolve());
-            if (typeof node.thedef.init !== "undefined") {
+            if (!redefine(node, node.scope.parent_scope.resolve())) {
+                delete def.defun;
+            } else if (typeof node.thedef.init !== "undefined") {
                 node.thedef.init = false;
             } else if (def.init) {
                 node.thedef.init = def.init;
@@ -332,7 +333,7 @@ AST_Toplevel.DEFMETHOD("figure_out_scope", function(options) {
         var old_def = node.thedef;
         if (!all(old_def.orig, function(sym) {
             return !(sym instanceof AST_SymbolConst || sym instanceof AST_SymbolLet);
-        })) return;
+        })) return false;
         var new_def = scope.find_variable(name);
         if (new_def) {
             var redef = new_def.redefined();
@@ -352,6 +353,7 @@ AST_Toplevel.DEFMETHOD("figure_out_scope", function(options) {
             node.reference(options);
         });
         if (new_def.undeclared) self.variables.set(name, new_def);
+        return true;
     }
 });