[processing] Fix crash when an algorithm dialog is left open and

processing options are changed

Make sure the algorithm dialogs use their own copy of algorithms,
instead of the copies owned by the processing registry. Opening
processing options triggers a full reload of providers, deleting
all existing algorithm instances from the registry first.

python/plugins/processing/gui/ProcessingToolbox.py

@@ -201,7 +201,7 @@ def showPopupMenu(self, point):
             popupmenu.exec_(self.algorithmTree.mapToGlobal(point))
 
     def editRenderingStyles(self):
-        alg = self.algorithmTree.selectedAlgorithm()
+        alg = self.algorithmTree.selectedAlgorithm().create() if self.algorithmTree.selectedAlgorithm() is not None else None
         if alg is not None:
             dlg = EditRenderingStylesDialog(alg)
             dlg.exec_()
@@ -210,14 +210,14 @@ def activateCurrent(self):
         self.executeAlgorithm()
 
     def executeAlgorithmAsBatchProcess(self):
-        alg = self.algorithmTree.selectedAlgorithm()
+        alg = self.algorithmTree.selectedAlgorithm().create() if self.algorithmTree.selectedAlgorithm() is not None else None
         if alg is not None:
             dlg = BatchAlgorithmDialog(alg)
             dlg.show()
             dlg.exec_()
 
     def executeAlgorithm(self):
-        alg = self.algorithmTree.selectedAlgorithm()
+        alg = self.algorithmTree.selectedAlgorithm().create() if self.algorithmTree.selectedAlgorithm() is not None else None
         if alg is not None:
             ok, message = alg.canExecute()
             if not ok:

python/plugins/processing/tools/general.py

@@ -127,7 +127,7 @@ def createAlgorithmDialog(algOrName, parameters={}):
     and delete this dialog.
     """
     if isinstance(algOrName, QgsProcessingAlgorithm):
-        alg = algOrName
+        alg = algOrName.create()
     else:
         alg = QgsApplication.processingRegistry().createAlgorithmById(algOrName)