Included the missing declaration of the dictionary
@@ -20,6 +20,7 @@ class PlotFlowField(BaseSolver):
settings_types = dict()
settings_default = dict()
settings_description = dict()
+ settings_options = dict()
settings_types['postproc_grid_generator'] = 'str'
settings_default['postproc_grid_generator'] = 'GridBox'
