get_participants cannot handle lists of non-strings

[jakob-weiss]

(Probably related to #32)

I recently added a column containing lists of ints to the participant table, and now get_participants fails:

-> 1378 df = df.applymap(lambda x: [i['entityName'] if 'entityName' in i else i for i in x] 1379 if isinstance(x, list) and np.all(pd.notnull(x)) else x)

... (long stack trace) ...

TypeError: argument of type 'int' is not iterable