From dedf9789485eb9110f02b46dcbb8d9a26e7aea6f Mon Sep 17 00:00:00 2001
From: Bruno Windels <brunow@matrix.org>
Date: Thu, 11 Jul 2019 18:33:22 +0200
Subject: [PATCH] prevent inserting parts at index -1 for empty documents

---
 src/editor/model.js | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/editor/model.js b/src/editor/model.js
index 778797dad2..4e39c70c4c 100644
--- a/src/editor/model.js
+++ b/src/editor/model.js
@@ -244,6 +244,10 @@ export default class EditorModel {
                 addLen += part.text.length - offset;
                 index += 1;
             }
+        } else if (index < 0) {
+            // if position was not found (index: -1, as happens for empty editor)
+            // reset it to insert as first part
+            index = 0;
         }
         while (str) {
             const newPart = this._partCreator.createPartForInput(str);