Mobile,Desktop: Fixes #9971: Fix auto-indentation in some types of code blocks (#9972)

packages/editor/CodeMirror/markdown/codeBlockLanguages/defaultLanguage.ts

@@ -0,0 +1,18 @@
+import { LanguageDescription, LanguageSupport, StreamLanguage } from '@codemirror/language';
+
+// To allow auto-indent to work in an unrecognised language, we define an
+// empty language. Doing so seems to enable auto-indent in code blocks with
+// that language.
+const defaultLangauge = StreamLanguage.define({
+	token: (stream) => {
+		stream.next();
+		return null;
+	},
+});
+
+const defaultLanguageDescription = LanguageDescription.of({
+	name: 'default',
+	support: new LanguageSupport(defaultLangauge),
+});
+
+export default defaultLanguageDescription;