Do not call loadRequest on an invalid URL

I expected that error to be handled gracefully. It's actually not, it
crashes the whole browser, and saves a state that will make it crash
again on startup. So just ignore invalid URLs if searchFromAddressBar is
set to false.

src/lib/webengine/webview.cpp

@@ -192,11 +192,7 @@ void WebView::load(const LoadRequest &request)
     if (qzSettings->searchFromAddressBar) {
         const LoadRequest searchRequest = mApp->searchEnginesManager()->searchResult(request.urlString());
         loadRequest(searchRequest);
-        return;
     }
-
-    // This will produce an error, but the user requested so by disabling "search from address bar"
-    loadRequest(request);
 }
 
 bool WebView::isLoading() const