fix corner cases with `export default` (#4673)

1 files changed, 6 insertions, 2 deletions

diff --git a/lib/ast.js b/lib/ast.js
index b386b442..18169dfd 100644
--- a/lib/ast.js
+++ b/lib/ast.js
@@ -1060,7 +1060,7 @@ var AST_ExportDeclaration = DEFNODE("ExportDeclaration", "body", {
 var AST_ExportDefault = DEFNODE("ExportDefault", "body", {
     $documentation: "An `export default` statement",
     $propdoc: {
-        body: "[AST_Node] an expression node (should not be instanceof AST_Statement)",
+        body: "[AST_Node] the default export",
     },
     walk: function(visitor) {
         var node = this;
@@ -1069,7 +1069,11 @@ var AST_ExportDefault = DEFNODE("ExportDefault", "body", {
         });
     },
     _validate: function() {
-        must_be_expression(this, "body");
+        if (this.body instanceof AST_Lambda && this.body.name) {
+            if (!(this.body instanceof AST_LambdaDefinition)) throw new Error("body must be AST_LambdaDefinition");
+        } else {
+            must_be_expression(this, "body");
+        }
     },
 }, AST_Statement);