From e9c23ba7a1b4227024d61b8d3919ac8060fd3f42 Mon Sep 17 00:00:00 2001
From: Sam Goldman <samwgoldman@gmail.com>
Date: Wed, 23 Dec 2015 16:37:14 -0500
Subject: [PATCH] Don't generate class mixins if prop doesn't exist

---
 packages/babel-generator/src/generators/flow.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/packages/babel-generator/src/generators/flow.js b/packages/babel-generator/src/generators/flow.js
index decdde9d74..b20ebe593a 100644
--- a/packages/babel-generator/src/generators/flow.js
+++ b/packages/babel-generator/src/generators/flow.js
@@ -104,7 +104,7 @@ export function _interfaceish(node: Object) {
     this.push(" extends ");
     this.printJoin(node.extends, node, { separator: ", " });
   }
-  if (node.mixins.length) {
+  if (node.mixins && node.mixins.length) {
     this.push(" mixins ");
     this.printJoin(node.mixins, node, { separator: ", " });
   }