From 8db216c7f665751fba804d7b07e02a925bf62a17 Mon Sep 17 00:00:00 2001
From: Andrew Bradley <cspotcode@gmail.com>
Date: Mon, 13 Jan 2020 13:05:08 -0500
Subject: [PATCH] Downgrade `yn` due to node engine (#942)

---
 package-lock.json |  6 +++---
 package.json      |  2 +-
 src/index.ts      | 10 +++++++++-
 3 files changed, 13 insertions(+), 5 deletions(-)

diff --git a/package-lock.json b/package-lock.json
index 932afdb03..49a55b1f2 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -2090,9 +2090,9 @@
       }
     },
     "yn": {
-      "version": "4.0.0",
-      "resolved": "https://registry.npmjs.org/yn/-/yn-4.0.0.tgz",
-      "integrity": "sha512-huWiiCS4TxKc4SfgmTwW1K7JmXPPAmuXWYy4j9qjQo4+27Kni8mGhAAi1cloRWmBe2EqcLgt3IGqQoRL/MtPgg=="
+      "version": "3.1.1",
+      "resolved": "https://registry.npmjs.org/yn/-/yn-3.1.1.tgz",
+      "integrity": "sha512-Ux4ygGWsu2c7isFWe8Yu1YluJmqVhxqK2cLXNQA5AcC3QfbGNpM7fu0Y8b/z16pXLnFxZYvWhd3fhBY9DLmC6Q=="
     }
   }
 }
diff --git a/package.json b/package.json
index df977e0b3..5a76795cb 100644
--- a/package.json
+++ b/package.json
@@ -83,6 +83,6 @@
     "diff": "^4.0.1",
     "make-error": "^1.1.1",
     "source-map-support": "^0.5.6",
-    "yn": "^4.0.0"
+    "yn": "3.1.1"
   }
 }
diff --git a/src/index.ts b/src/index.ts
index 790c36f9a..885b0b819 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -1,6 +1,6 @@
 import { relative, basename, extname, resolve, dirname, join } from 'path'
 import sourceMapSupport = require('source-map-support')
-import * as yn from 'yn'
+import * as ynModule from 'yn'
 import { BaseError } from 'make-error'
 import * as util from 'util'
 import * as _ts from 'typescript'
@@ -26,6 +26,14 @@ declare global {
  */
 export const INSPECT_CUSTOM = util.inspect.custom || 'inspect'
 
+/**
+ * Wrapper around yn module that returns `undefined` instead of `null`.
+ * This is implemented by yn v4, but we're staying on v3 to avoid v4's node 10 requirement.
+ */
+function yn (value: string | undefined) {
+  return ynModule(value) ?? undefined
+}
+
 /**
  * Debugging `ts-node`.
  */