From 1ed32e3db7e35da706143233d3b262b3dbb737cb Mon Sep 17 00:00:00 2001
From: Neil Jenkins <neil@nmjenkins.com>
Date: Mon, 9 Oct 2023 11:52:58 +1100
Subject: [PATCH] Squire: Fix crash removing formatting

The fixer node may get removed when merging adjacent inlines, so move
the cleanup to before this. For safety, also properly check for non-null
nodes so we don't crash if it's still elided for some reason.
---
 source/Editor.ts          | 28 +++++++++++++++-------------
 source/node/Whitespace.ts |  2 +-
 2 files changed, 16 insertions(+), 14 deletions(-)

diff --git a/source/Editor.ts b/source/Editor.ts
index 0b3fa64..94b5859 100644
--- a/source/Editor.ts
+++ b/source/Editor.ts
@@ -1524,7 +1524,7 @@ class Squire {
 
         // We need a node in the selection to break the surrounding
         // formatted text.
-        let fixer: Node | Text | undefined;
+        let fixer: Node | Text | null | undefined;
         if (range.collapsed) {
             if (cantFocusEmptyTextNodes) {
                 fixer = document.createTextNode(ZWS);
@@ -1615,6 +1615,20 @@ class Squire {
             replaceWith(el, empty(el));
         });
 
+        if (cantFocusEmptyTextNodes && fixer) {
+            // Clean up any previous ZWS in this block. They are not needed,
+            // and this works around a Chrome bug where it doesn't render the
+            // text in some situations with multiple ZWS(!)
+            fixer = fixer.parentNode;
+            let block = fixer;
+            while (block && isInline(block)) {
+                block = block.parentNode;
+            }
+            if (block) {
+                removeZWS(block, fixer);
+            }
+        }
+
         // Merge adjacent inlines:
         this._getRangeAndRemoveBookmark(range);
         if (fixer) {
@@ -1622,18 +1636,6 @@ class Squire {
         }
         mergeInlines(root, range);
 
-        if (cantFocusEmptyTextNodes && fixer) {
-            // Clean up any previous ZWS in this block. They are not needed,
-            // and this works around a Chrome bug where it doesn't render the
-            // text in some situations with multiple ZWS(!)
-            fixer = fixer.parentNode!;
-            let block = fixer;
-            while (isInline(block)) {
-                block = block.parentNode!;
-            }
-            removeZWS(block, fixer);
-        }
-
         return range;
     }
 
diff --git a/source/node/Whitespace.ts b/source/node/Whitespace.ts
index 38e4ea7..b46326f 100644
--- a/source/node/Whitespace.ts
+++ b/source/node/Whitespace.ts
@@ -34,7 +34,7 @@ const isLineBreak = (br: Element, isLBIfEmptyBlock: boolean): boolean => {
 // contained ZWS space then remove it too. We may want to keep one ZWS node at
 // the bottom of the tree so the block can be selected. Define that node as the
 // keepNode.
-const removeZWS = (root: Node, keepNode?: Node): void => {
+const removeZWS = (root: Node, keepNode?: Node | null): void => {
     const walker = new TreeIterator<Text>(root, SHOW_TEXT);
     let textNode: Text | null;
     let index: number;