Fix crash on exit

python/plugins/processing/gui/ProcessingToolbox.py

@@ -139,7 +139,8 @@ def addProviderActions(self, provider):
 
     def addProvider(self, provider_id):
         provider = QgsApplication.processingRegistry().providerById(provider_id)
-        self.addProviderActions(provider)
+        if provider is not None:
+            self.addProviderActions(provider)
 
     def removeProvider(self, provider_id):
         button = self.findChild(QToolButton, 'provideraction-' + provider_id)

src/gui/processing/qgsprocessingtoolboxmodel.cpp

@@ -165,7 +165,8 @@ void QgsProcessingToolboxModel::repopulateRecentAlgorithms( bool resetting )
 
   if ( !mRegistry )
   {
-    emit recentAlgorithmAdded();
+    if ( !resetting )
+      emit recentAlgorithmAdded();
     return;
   }
 
@@ -181,7 +182,8 @@ void QgsProcessingToolboxModel::repopulateRecentAlgorithms( bool resetting )
 
   if ( recentAlgorithms.empty() )
   {
-    emit recentAlgorithmAdded();
+    if ( !resetting )
+      emit recentAlgorithmAdded();
     return;
   }
 
@@ -199,8 +201,8 @@ void QgsProcessingToolboxModel::repopulateRecentAlgorithms( bool resetting )
   if ( !resetting )
   {
     endInsertRows();
+    emit recentAlgorithmAdded();
   }
-  emit recentAlgorithmAdded();
 }
 
 void QgsProcessingToolboxModel::providerAdded( const QString &id )