From 7143cc7aa4ac7710372219440ea234fc82edc64a Mon Sep 17 00:00:00 2001
From: Kohei Ueno <kohei.ueno119@gmail.com>
Date: Tue, 28 Jun 2022 19:10:50 +0900
Subject: [PATCH] readline: fix to not access a property on an undefined value
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PR-URL: https://github.com/nodejs/node/pull/43543
Reviewed-By: Antoine du Hamel <duhamelantoine1995@gmail.com>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>
Reviewed-By: Yongsheng Zhang <zyszys98@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
---
 lib/internal/readline/utils.js                |  3 +++
 .../test-repl-tab-complete-on-editor-mode.js  | 21 +++++++++++++++++++
 2 files changed, 24 insertions(+)
 create mode 100644 test/parallel/test-repl-tab-complete-on-editor-mode.js

diff --git a/lib/internal/readline/utils.js b/lib/internal/readline/utils.js
index 55b3e07b4c1782..98679494a3e64b 100644
--- a/lib/internal/readline/utils.js
+++ b/lib/internal/readline/utils.js
@@ -366,6 +366,9 @@ function* emitKeys(stream) {
 
 // This runs in O(n log n).
 function commonPrefix(strings) {
+  if (strings.length === 0) {
+    return '';
+  }
   if (strings.length === 1) {
     return strings[0];
   }
diff --git a/test/parallel/test-repl-tab-complete-on-editor-mode.js b/test/parallel/test-repl-tab-complete-on-editor-mode.js
new file mode 100644
index 00000000000000..610724de2a2844
--- /dev/null
+++ b/test/parallel/test-repl-tab-complete-on-editor-mode.js
@@ -0,0 +1,21 @@
+'use strict';
+
+require('../common');
+const ArrayStream = require('../common/arraystream');
+const repl = require('repl');
+
+const stream = new ArrayStream();
+const replServer = repl.start({
+  input: stream,
+  output: stream,
+  terminal: true,
+});
+
+// Editor mode
+replServer.write('.editor\n');
+
+// Regression test for https://github.com/nodejs/node/issues/43528
+replServer.write('a');
+replServer.write(null, { name: 'tab' }); // Should not throw
+
+replServer.close();