server: reset counter related to kill-switch on client error (#20513)

* server: reset kill-switch on client error

This avoids triggering a server kill switch.

If the client sends a request that exceeds the configured context size, an appropriate HTTP 400 response is provided and no tokens are generated.

However since no tokens are generated, update_slots() increments n_empty_consecutive. If the client sends 3 such messages in a row, the server terminates.

* moved counter reset as per recommendation

* cont : minor

---------

Co-authored-by: Georgi Gerganov <ggerganov@gmail.com>

tools/server/server-context.cpp

@@ -1189,6 +1189,9 @@ private:
             ? SLOT_STATE_WAIT_OTHER // wait for the parent to process prompt
             : SLOT_STATE_STARTED;
 
+        // reset server kill-switch counter
+        n_empty_consecutive = 0;
+
         SLT_INF(slot, "processing task, is_child = %d\n", slot.task->is_child());
         return true;
     }