Fix a11y checker refusing to close in NQ

flag=none
fixes RCX-1836

Test Plan:
 - Copy RCE changes into NQ
 - In NQ, open an RCE, open a11y checker
 - Click off RCE so it collapses
 - Re-open RCE and a11y checker
 - Click off RCE so it collapses
 - Close the a11y checker
 * Verify it closes

Change-Id: Icb78b6924f8228c5fb2a9da9d0a2f1248b731f88
Reviewed-on: https://gerrit.instructure.com/c/canvas-lms/+/348486
Tested-by: Service Cloud Jenkins <svc.cloudjenkins@instructure.com>
Reviewed-by: Mysti Lilla <mysti@instructure.com>
QA-Review: Mysti Lilla <mysti@instructure.com>
Product-Review: Jacob DeWar <jacob.dewar@instructure.com>

packages/canvas-rce/CHANGELOG.md

@@ -5,26 +5,32 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [Unreleased]
+
+### Fixed
+
+- A11y checker tray refusing to close in New Quizzes
+
 ## 5.13.0 - 2024-05-14
 
 ### Added
 
--	Find and Replace Tray
--	Support for Bahasa Indonesia Language and Irish (Gaeilge) Language
--	Support for tools to always be present in toolbar
--	LTI enhancements
+- Find and Replace Tray
+- Support for Bahasa Indonesia Language and Irish (Gaeilge) Language
+- Support for tools to always be present in toolbar
+- LTI enhancements
 
 ### Changed
 
--	Limited list of fonts to self-hosted and websafe
--	Preferred HTML editor stored in localstorage
--	Stopped adding aria-hidden to RCE’s parent label
+- Limited list of fonts to self-hosted and websafe
+- Preferred HTML editor stored in localstorage
+- Stopped adding aria-hidden to RCE’s parent label
 
 ### Fixed
 
 - Focus properly restored after closing a11y checker
--	Allow non relative video srcs when editing captions
--	Enhanced user content now translated correctly
+- Allow non relative video srcs when editing captions
+- Enhanced user content now translated correctly
 
 ## 5.12.2 - 2024-01-31
 
@@ -57,7 +63,6 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Show media captions in New Quizzes
 - Bump Instui to 8.49
 
-
 ## 5.11.1 - 2023-10-12
 
 ### Fixed

packages/canvas-rce/src/rce/plugins/tinymce-a11y-checker/utils/__tests__/indicate.test.js

@@ -88,4 +88,8 @@ describe('clearIndicators', () => {
     clearIndicators(document)
     expect(document.getElementById(A11Y_CHECKER_STYLE_ELEM_ID).textContent).toEqual('')
   })
+
+  it('does not throw when doc null', () => {
+    expect(() => clearIndicators(null)).not.toThrow()
+  })
 })

packages/canvas-rce/src/rce/plugins/tinymce-a11y-checker/utils/indicate.js

@@ -31,7 +31,7 @@ export const A11Y_CHECKER_STYLE_ELEM_ID = 'a11y-checker-style'
 // Remove the current indicator(s) by removing the contents of
 // the style element
 export function clearIndicators(doc) {
-  const checker_style = doc.getElementById(A11Y_CHECKER_STYLE_ELEM_ID)
+  const checker_style = doc?.getElementById(A11Y_CHECKER_STYLE_ELEM_ID)
   if (checker_style) {
     checker_style.textContent = ''
   }