fix corner case in `booleans` (#4375)

fixes #4374

1 files changed, 7 insertions, 8 deletions

diff --git a/lib/ast.js b/lib/ast.js
index 262372ee..31281c1e 100644
--- a/lib/ast.js
+++ b/lib/ast.js
@@ -1451,14 +1451,13 @@ TreeWalker.prototype = {
                 || p.tail_node() === self) {
                 self = p;
             } else if (p instanceof AST_Return) {
-                var fn;
-                do {
-                    fn = this.parent(++i);
-                    if (!fn) return false;
-                } while (!(fn instanceof AST_Lambda));
-                if (fn.name) return false;
-                self = this.parent(++i);
-                if (!self || self.TYPE != "Call" || self.expression !== fn) return false;
+                for (var call, fn = p; call = this.parent(++i); fn = call) {
+                    if (call.TYPE == "Call") {
+                        if (!(fn instanceof AST_Lambda) || fn.name) return false;
+                    } else if (fn instanceof AST_Lambda) {
+                        return false;
+                    }
+                }
             } else {
                 return false;
             }