Major Description
Initialized in Koalas issue: https://github.com/databricks/koalas/issues/1888
The `(Series|DataFrame).describe()` in pandas API on Spark doesn't work properly when DataFrame has no numeric column.
>>> df = ps.DataFrame({'a': ["a", "b", "c"]})
>>> df.describe()
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "/.../python/pyspark/pandas/frame.py", line 7582, in describe
raise ValueError("Cannot describe a DataFrame without columns")
ValueError: Cannot describe a DataFrame without columns
As it works fine in pandas, we should fix it.
