Beta editor: Opening, then closing settings, can break some legacy plugins

[personalizedrefrigerator]

Operating system

Linux

Joplin version

2.14.16

Desktop version info

No response

Current behaviour

1. Apply the following diff:

diff --git a/packages/app-cli/tests/support/plugins/codemirror6/src/contentScript.ts b/packages/app-cli/tests/support/plugins/codemirror6/src/contentScript.ts
index af0532dcf..3a816a16c 100644
--- a/packages/app-cli/tests/support/plugins/codemirror6/src/contentScript.ts
+++ b/packages/app-cli/tests/support/plugins/codemirror6/src/contentScript.ts
@@ -47,7 +47,7 @@ export default (_context: ContentScriptContext): CodeMirrorContentScriptModule =
 
 			// We can also register editor commands. These commands can be later executed with:
 			//   joplin.commands.execute('editor.execCommand', { name: 'name-here', args: [] })
-			codeMirrorWrapper.registerCommand('wrap-selection-with-tag', (tagName: string) => {
+			(codeMirrorWrapper as any).defineExtension('wrap-selection-with-tag', (tagName: string) => {
 				const editor: EditorView = codeMirrorWrapper.editor;
 
 				// See https://codemirror.net/examples/change/

2. Build and add the CodeMirror 6 demo plugin (packages/app-cli/tests/support/plugins/codemirror6/) as a development plugin.
3. Verify that running :underline from the command palette works.
4. Open settings
5. Close settings
6. Verify that running :underline from the command palette no longer works.

Expected behaviour

Currently, CodeMirror5Emulation.defineExtension only works if the extension is not already present. This is different from the behavior of .defineExtension in CodeMirror 5, which overrides previous extension values.

Note: This is breaking a downstream pull request in some cases.

Logs

No response