Hello, When attempting to export an xdi file for a pre-edge peak fit in XAS viewer, the error message below prints to the terminal and the xdi file is not generated. I can provide the project file and instructions for generating the error message if that would be helpful. Thank you, George Traceback (most recent call last): File "/anaconda3/lib/python3.7/site-packages/larch/wxxas/prepeak_panel.py", line 369, in onExportFitResult yerr=yerr, x=x) File "/anaconda3/lib/python3.7/site-packages/larch/io/export_modelresult.py", line 60, in export_modelresult delta_fit = result.eval_uncertainty(result.params, **kwargs) File "/anaconda3/lib/python3.7/site-packages/lmfit/model.py", line 1488, in eval_uncertainty dval = pars[pname].stderr/3.0 TypeError: unsupported operand type(s) for /: 'NoneType' and 'float'