From 094ef31c01f7f65a3f44d608a87671fa90eff199 Mon Sep 17 00:00:00 2001
From: James DiGioia <james.digioia@valtech.com>
Date: Sun, 22 Jul 2018 18:50:29 -0400
Subject: [PATCH] Wrap callback in try/finally

This ensures we clean up always if the callback throws.
---
 packages/babel-parser/src/parser/expression.js | 18 ++++++++++--------
 1 file changed, 10 insertions(+), 8 deletions(-)

diff --git a/packages/babel-parser/src/parser/expression.js b/packages/babel-parser/src/parser/expression.js
index b04e26bac3..47a34a18ea 100644
--- a/packages/babel-parser/src/parser/expression.js
+++ b/packages/babel-parser/src/parser/expression.js
@@ -2131,10 +2131,11 @@ export default class ExpressionParser extends LValParser {
       maxTopicIndex: null,
     };
 
-    const callbackResult = callback();
-
-    this.state.topicContext = outerContextTopicState;
-    return callbackResult;
+    try {
+      return callback();
+    } finally {
+      this.state.topicContext = outerContextTopicState;
+    }
   }
 
   // Disable topic references from outer contexts within syntax constructs
@@ -2153,10 +2154,11 @@ export default class ExpressionParser extends LValParser {
       maxTopicIndex: null,
     };
 
-    const callbackResult = callback();
-
-    this.state.topicContext = outerContextTopicState;
-    return callbackResult;
+    try {
+      return callback();
+    } finally {
+      this.state.topicContext = outerContextTopicState;
+    }
   }
 
   // Register the use of a primary topic reference (`#`) within the current