give more useful error output if there is no measurement file for thellier_gui.py
give more useful error output if there is no measurement file for thellier_gui.py
lfairchild/PmagPy,Caoimhinmg/PmagPy,Caoimhinmg/PmagPy,lfairchild/PmagPy,lfairchild/PmagPy,Caoimhinmg/PmagPy