From 8a88e3398b4cf587be2da606d126feebefad1e4f Mon Sep 17 00:00:00 2001
From: Logan Smyth <loganfsmyth@gmail.com>
Date: Thu, 8 Nov 2018 20:03:38 -0800
Subject: [PATCH] Ensure that the arrow nodes have a location before using
 them.

---
 packages/babel-generator/src/generators/methods.js | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/packages/babel-generator/src/generators/methods.js b/packages/babel-generator/src/generators/methods.js
index 9d9f68733380..1019aba04c7c 100644
--- a/packages/babel-generator/src/generators/methods.js
+++ b/packages/babel-generator/src/generators/methods.js
@@ -113,10 +113,12 @@ export function ArrowFunctionExpression(node: Object) {
   ) {
     if (
       this.format.retainLines &&
+      node.loc &&
+      node.body.loc &&
       node.loc.start.line < node.body.loc.start.line
     ) {
       this.token("(");
-      if (firstParam.loc.start.line > node.loc.start.line) {
+      if (firstParam.loc && firstParam.loc.start.line > node.loc.start.line) {
         this.indent();
         this.print(firstParam, node);
         this.dedent();