castle-search: read Brave again, and report genuine zero-hit searches as such

Brave: #results no longer exists on the live page; fall back to #main/main.
It was reported as 'no results area at all', i.e. a rate limit.

DuckDuckGo: its 'No results found' notice is itself a .result, so an empty
search looked like broken markup. emptyMarker lets the probe say the engine
itself reported no matches, and the error tells the caller to loosen the
query instead of switching engines.

1 files changed, 12 insertions, 0 deletions

diff --git a/castle-search/src/search.ts b/castle-search/src/search.ts
index 1c84392..c64735d 100644
--- a/castle-search/src/search.ts
+++ b/castle-search/src/search.ts
@@ -299,6 +299,18 @@ export const search = async (
         });
       }
 
+      if (probe.results.length === 0 && probe.empty) {
+        // The engine itself says nothing matched. That is the query's doing, not
+        // the extractor's or a rate limit's, and saying so stops the caller from
+        // switching engines for a query no index will answer.
+        throw new NoResultsError(
+          `${engine.label} reports no matches for this query (${probe.url || searchUrl}). The page loaded ` +
+            `normally and the engine says so itself, so this is not a block or a broken extractor — the query ` +
+            `is too narrow. Drop the quotes or some of the terms; retrying another engine with the same ` +
+            `over-specific query is unlikely to help.`,
+        );
+      }
+
       if (probe.results.length === 0) {
         // "container missing entirely" and "container present but empty" are
         // different faults, and saying which saves the next person a browser