Fix possible bug with attributes in increment

ush/python/pygfs/task/analysis.py

@@ -86,7 +86,7 @@ def add_fv3_increments(self, inc_file_tmpl: str, bkg_file_tmpl: str, incvars: Li
                     rstfile.variables[vname][:] = anl[:]
                     try:
                         rstfile.variables[vname].delncattr('checksum')  # remove the checksum so fv3 does not complain
-                    except AttributeError:
+                    except (AttributeError, RuntimeError):
                         pass  # checksum is missing, move on
 
     @logit(logger)