fix: Prevent ISE when tsquery tail interleaves operator and escape chars (#12475)

When a user query produces a pg-tsquery output ending in mixed `&` and `\`
characters (e.g. `"plugins"&\`), stripping them with separate single-char
regexes in a fixed order could leave a dangling `&` operator, causing
Postgres to reject the query with "no operand in tsquery".

Co-authored-by: Claude Opus 4.7 <noreply@anthropic.com>

plugins/search-postgres/server/PostgresSearchProvider.test.ts

@@ -1412,5 +1412,13 @@ describe("PostgresSearchProvider", () => {
         `"this<->is<->a<->test"`
       );
     });
+    it("should strip interleaved trailing operator and escape characters", () => {
+      // pg-tsquery reorders trailing operators and may emit a tail like
+      // `&\` that, if stripped one character at a time in the wrong order,
+      // leaves a dangling `&` and triggers "no operand in tsquery".
+      expect(PostgresSearchProvider.webSearchQuery(`"plugins"\\&`)).toBe(
+        `"plugins"`
+      );
+    });
   });
 });

plugins/search-postgres/server/PostgresSearchProvider.ts

@@ -861,10 +861,10 @@ export default class PostgresSearchProvider extends BaseSearchProvider {
         // spaces. Ref: https://github.com/caub/pg-tsquery/issues/27
         quotedSearch ? limitedQuery.trim() : `${limitedQuery.trim()}*`
       )
-        // Remove any trailing join characters
-        .replace(/&$/, "")
-        // Remove any trailing escape characters
-        .replace(/\\$/, "")
+        // Strip any trailing join (&) or escape (\) characters, in any
+        // combination, so we never hand to_tsquery an operator with no
+        // operand (e.g. a tail of "&\" would leave a dangling "&").
+        .replace(/[&\\]+$/, "")
     );
   }