fix(endpoint-discovery): delete failed cache entry in blocking operations

Author: kuhe

packages/middleware-endpoint-discovery/src/updateDiscoveredEndpointInCache.ts

@@ -76,6 +76,11 @@ export const updateDiscoveredEndpointInCache = async (
           }
 
           if (options.isDiscoveredEndpointRequired) {
+            // The cache entry must be deleted in this case
+            // because a subsequent blocking request will be stuck
+            // in a waiting state if it sees the cache entry
+            // but we have already flushed the request queue. 
+            endpointCache.delete(cacheKey);
             reject(errorToThrow);
           } else {
             // Endpoint Discovery is optional. No error needs to be thrown.