- [GUI] prevent rendering of lines in the queue when corresponding

stream has been canceled;
- [GUI] print an error when opening a non existent local path.

src/gui/client/main-window.lisp

@@ -79,7 +79,8 @@
   (with-accessors ((fetching-thread fetching-thread)) object
       (abort-downloading object)
     (when (bt:threadp fetching-thread)
-      (bt:join-thread fetching-thread))))
+      (bt:join-thread fetching-thread)))
+  object)
 
 (defmethod stop-stream-thread ((object string))
   (let ((stream-wrapper (find-db-stream-url object)))
@@ -444,7 +445,9 @@
              (clean-gemtext main-window)
              (set-text-gemtext main-window lines)))))
     ((fs:directory-exists-p path)
-     (gui:choose-directory :initial-dir path :parent main-window :mustexist t))))
+     (gui:choose-directory :initial-dir path :parent main-window :mustexist t))
+    (t
+     (notify-request-error (format nil (_ "No such file or directory: ~a") path)))))
 
 (defun open-iri (iri main-window use-cache)
   (handler-case
@@ -495,13 +498,21 @@
         ((gemini-client:header-success-p status-code)
          (cond
            ((eq status +stream-status-streaming+)
-            (maybe-stop-steaming-stream-thread)
-            (clean-gemtext main-window)
-            (start-streaming-thread iri
-                                    :use-cache        nil
-                                    :process-function (lambda (lines)
-                                                        (collect-ir-lines iri main-window lines))
-                                    :status           status))
+            (let ((stopped-stream (maybe-stop-steaming-stream-thread)))
+              (clean-gemtext main-window)
+              (start-streaming-thread iri
+                                      :use-cache        nil
+                                      :process-function
+                                      (lambda (lines)
+                                        ;; this test  ensures that the
+                                        ;; collecting  events left  on
+                                        ;; the queue won't be actually
+                                        ;; processed, just discarded
+                                        (when (and stopped-stream
+                                                   (not (eq (status stopped-stream)
+                                                            +stream-status-canceled+)))
+                                          (collect-ir-lines iri main-window lines)))
+                                      :status           status)))
            ((eq status +stream-status-downloading+)
             (when (not (find-db-stream-url iri))
               (enqueue-request-notify-error :gemini-request 1 iri use-cache)))