Traceback (most recent call last):
  File "/opt/conda/lib/python3.6/site-packages/pandas/core/indexes/base.py", line 3118, in get_value
    tz=getattr(series.dtype, 'tz', None))
  File "pandas/_libs/index.pyx", line 106, in pandas._libs.index.IndexEngine.get_value
  File "pandas/_libs/index.pyx", line 114, in pandas._libs.index.IndexEngine.get_value
  File "pandas/_libs/index.pyx", line 162, in pandas._libs.index.IndexEngine.get_loc
  File "pandas/_libs/hashtable_class_helper.pxi", line 958, in pandas._libs.hashtable.Int64HashTable.get_item
  File "pandas/_libs/hashtable_class_helper.pxi", line 964, in pandas._libs.hashtable.Int64HashTable.get_item
KeyError: 0

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "bikeshare.py", line 185, in <module>
    main()
  File "bikeshare.py", line 174, in main
    time_stats(df)
  File "bikeshare.py", line 87, in time_stats
    common_month = df['month'].mode()[0]
  File "/opt/conda/lib/python3.6/site-packages/pandas/core/series.py", line 767, in __getitem__
    result = self.index.get_value(self, key)
  File "/opt/conda/lib/python3.6/site-packages/pandas/core/indexes/base.py", line 3124, in get_value
    return libindex.get_value_box(s, key)
  File "pandas/_libs/index.pyx", line 55, in pandas._libs.index.get_value_box
  File "pandas/_libs/index.pyx", line 70, in pandas._libs.index.get_value_box
IndexError: index out of bounds