Merge pull request #255 from datafold/fix_oct13

Bugfix: Joindiff crashed when no numeric columns were used.

Author: erezsh

data_diff/joindiff_tables.py

@@ -34,7 +34,11 @@
 
 def merge_dicts(dicts):
  i = iter(dicts)
- res = next(i)
+ try:
+ res = next(i)
+ except StopIteration:
+ return {}
+
  for d in i:
  res.update(d)
  return res