Fix crash when closing tab during a search

qutebrowser/browser/webengine/webenginetab.py

@@ -183,6 +183,13 @@ class WebEngineSearch(browsertab.AbstractSearch):
                                       self._pending_searches))
                 return
 
+            if sip.isdeleted(self._widget):
+                # This happens when starting a search, and closing the tab
+                # before results arrive.
+                log.webview.debug("Ignoring finished search for deleted "
+                                  "widget")
+                return
+
             found_text = 'found' if found else "didn't find"
             if flags:
                 flag_text = 'with flags {}'.format(debug.qflags_key(

tests/end2end/features/search.feature

@@ -283,3 +283,9 @@ Feature: Searching on a page
         Then the following tabs should be open:
             - data/iframe_search.html
             - data/hello.txt (active)
+
+    Scenario: Closing a tab during a search
+        When I run :open -b about:blank
+        And I run :search a
+        And I run :tab-close
+        Then no crash should happen