fix replot on ref bug; better error msg for bad CIF import

Author: briantoby

GSASII/GSASIIpwdplot.py

@@ -1433,8 +1433,11 @@ def refPlotUpdate(Histograms,cycle=None,restore=False):
         DZ = (xye[1]-xye[3])*np.sqrt(xye[2])
         DifLine[0].set_xdata(X[Ibeg:Ifin])
         DifLine[0].set_ydata(DZ[Ibeg:Ifin])
-        lims = [min(DZ[Ibeg:Ifin]),max(DZ[Ibeg:Ifin])]
-        if all(np.isfinite(lims)): Plot1.set_ylim(lims)
+        try:
+            lims = [min(DZ[Ibeg:Ifin]),max(DZ[Ibeg:Ifin])]
+            if all(np.isfinite(lims)): Plot1.set_ylim(lims)
+        except:
+            pass
         CalcLine[0].set_xdata(X)
         ObsLine[0].set_xdata(X)
         BackLine[0].set_xdata(X)

GSASII/imports/G2phase_CIF.py

@@ -42,6 +42,7 @@ def __init__(self):
     def ContentsValidator(self, filename):
         fp = open(filename,'r')
         ok = self.CIFValidator(fp)
+        print('validator: ',ok)
         fp.close()
         return ok
 
@@ -75,7 +76,7 @@ def Reader(self,filename, ParentFrame=None, usedRanIdList=[], **unused):
         try:
             cf = G2obj.ReadCIF(filename)
         except cif.StarError as msg:
-            msg  = 'Unreadable cif file\n'+str(msg)
+            msg  = f'\nThis file does not have valid CIF syntax. Web site https://checkcif.iucr.org/ can help find CIF errors. If VESTA or https://addie.ornl.gov/conf_viewer is able to read this CIF, it may allow you to rewrite it as a valid file. \n\nError from PyCifRW: {msg}'
             self.errors = msg
             self.warnings += msg
             return False