fix(web): reuse CodeMirror search language

Author: brendan-kellam

packages/web/src/app/(app)/components/searchBar/zoektLanguageExtension.test.ts

@@ -0,0 +1,6 @@
+import { expect, test } from 'vitest';
+import { zoekt } from './zoektLanguageExtension';
+
+test('reuses the same language support across calls', () => {
+    expect(zoekt()).toBe(zoekt());
+});

packages/web/src/app/(app)/components/searchBar/zoektLanguageExtension.ts

@@ -1,7 +1,9 @@
 import { LanguageSupport, StreamLanguage } from "@codemirror/language";
 import { tags as t } from "@lezer/highlight";
 
-export const zoekt = () => {
+// StreamLanguage permanently registers a document NodeType, so this must be a
+// module singleton rather than one instance per SearchBar render.
+const zoektLanguageSupport = (() => {
     const zoektLanguage = StreamLanguage.define({
         startState() {
             return {
@@ -75,4 +77,6 @@ export const zoekt = () => {
     });
 
     return new LanguageSupport(zoektLanguage);
-};
+})();
+
+export const zoekt = () => zoektLanguageSupport;