# Buggy code
def __getitem__(self, key):
    kwargs = self._kwargs.copy()
    # Most of time indexing DataFrameGroupBy results in another DataFrameGroupBy object unless circumstances are
    # special in which case SeriesGroupBy has to be returned. Such circumstances are when key equals to a single
    # column name and is not a list of column names or list of one column name.
    make_dataframe = True
    if self._drop and self._as_index:
        if not isinstance(key, list):
            key = [key]
            kwargs["squeeze"] = True
            make_dataframe = False
    # When `as_index` is False, pandas will always convert to a `DataFrame`, we
    # convert to a list here so that the result will be a `DataFrame`.
    elif not self._as_index and not isinstance(key, list):
        # Sometimes `__getitem__` doesn't only get the item, it also gets the `by`
        # column. This logic is here to ensure that we also get the `by` data so
        # that it is there for `as_index=False`.
        if (
            isinstance(self._by, type(self._query_compiler))
            and all(c in self._columns for c in self._by.columns)
            and self._drop
        ):
            key = [key] + list(self._by.columns)
        else:
            key = [key]
    if isinstance(key, list) and (make_dataframe or not self._as_index):
        return DataFrameGroupBy(
            self._df[key],
            self._by,
            self._axis,
            idx_name=self._idx_name,
            drop=self._drop,
            **kwargs,
        )
    return SeriesGroupBy(
        self._df[key],
        self._by,
        self._axis,
        idx_name=self._idx_name,
        drop=False,
        **kwargs,
    )


# Traceback (IndexError)
pd_res:
population      GDP alpha-2
France    65000000  2583560      FR
Italy     59000000  1937894      IT
Malta       434000    12011      MT

md_res_partitions:
population      GDP alpha-2
France    65000000  2583560      FR
Italy     59000000  1937894      IT
Malta       434000    12011      MT

md_res:
distributed.worker - WARNING -  Compute Failed
Function:  apply_list_of_funcs
args:      ([[b"\x80\x04\x95\xb0\x03\x00\x00\x00\x00\x00\x00\x8c\x17cloudpickle.cloudpickle\x94\x8c\x0e_fill_function\x94\x93\x94(h\x00\x8c\x0f_make_skel_func\x94\x93\x94h\x00\x8c\r_builtin_type\x94\x93\x94\x8c\x08CodeType\x94\x85\x94R\x94(K\x01K\x00K\x01K\x05K\x13C\x14t\x00\xa0\x01|\x00j\x02\x88\x01\x88\x00f\x02\x19\x00\xa1\x01S\x00\x94N\x85\x94\x8c\x06pandas\x94\x8c\tDataFrame\x94\x8c\x04iloc\x94\x87\x94\x8c\x02df\x94\x85\x94\x8cZc:\\users\\dchigare\\desktop\\repos\\modin\\modin\\engines\\dask\\pandas_on_dask\\frame\\partition.py\x94\x8c\x08<lambda>\x94KcC\x00\x94\x8c\x0bcol_indices\x94\x8c\x0brow_indices\x94\x86\x94)t\x94R\x94K\x02}\x94(\x8c\x0b__package__\x94\x8c'modin.engines.dask.pandas_on_dask.frame\x94\x8c\x08__name__\x94\x8c1modin.engines.dask.pandas_on_dask.frame.partition\x94\x8c\x08__file__\x94h\x12u\x87\x94R\x94}\x94(\x8c\x07globals\x94}\x94h\x0ch\x00\x8c\tsubimport\x94\x93\x94h\x0c\x85\x94R\x94s\x8c\x08defaults\x94N\x8c\x04dict\x94}\x94\x8c\x0eclosure_values\x94]\x94(\x8c\x15numpy.c
kwargs:    {}
Exception: IndexError('positional indexers are out-of-bounds')

Traceback (most recent call last):
File "C:\Users\dchigare\Desktop\REPOS\TESTS\reprod.py", line 39, in <module>
print("\nmd_res:\n", md_res, sep="") # Exception: IndexError('positional indexers are out-of-bounds')
File "c:\users\dchigare\desktop\repos\modin\modin\pandas\base.py", line 3465, in __str__
return repr(self)
File "c:\users\dchigare\desktop\repos\modin\modin\pandas\dataframe.py", line 162, in __repr__
result = repr(self._build_repr_df(num_rows, num_cols))
File "c:\users\dchigare\desktop\repos\modin\modin\pandas\base.py", line 100, in _build_repr_df
return self.iloc[indexer]._query_compiler.to_pandas()
File "c:\users\dchigare\desktop\repos\modin\modin\backends\pandas\query_compiler.py", line 188, in to_pandas
return self._modin_frame.to_pandas()
File "c:\users\dchigare\desktop\repos\modin\modin\engines\base\frame\data.py", line 1350, in to_pandas
df = self._frame_mgr_cls.to_pandas(self._partitions)
File "c:\users\dchigare\desktop\repos\modin\modin\engines\base\frame\partition_manager.py", line 258, in to_pandas
retrieved_objects = [[obj.to_pandas() for obj in part] for part in partitions]
File "c:\users\dchigare\desktop\repos\modin\modin\engines\base\frame\partition_manager.py", line 258, in <listcomp>
retrieved_objects = [[obj.to_pandas() for obj in part] for part in partitions]
File "c:\users\dchigare\desktop\repos\modin\modin\engines\base\frame\partition_manager.py", line 258, in <listcomp>
retrieved_objects = [[obj.to_pandas() for obj in part] for part in partitions]
File "c:\users\dchigare\desktop\repos\modin\modin\engines\dask\pandas_on_dask\frame\partition.py", line 127, in to_pandas
dataframe = self.get()
File "c:\users\dchigare\desktop\repos\modin\modin\engines\dask\pandas_on_dask\frame\partition.py", line 63, in get
return self.future.result()
File "C:\Program Files (x86)\Microsoft Visual Studio\Shared\Python37_64\lib\site-packages\distributed\client.py", line 218, in result
raise exc.with_traceback(tb)
File "c:\users\dchigare\desktop\repos\modin\modin\engines\dask\pandas_on_dask\frame\partition.py", line 27, in apply_list_of_funcs
df = func(df, **kwargs)
File "c:\users\dchigare\desktop\repos\modin\modin\engines\dask\pandas_on_dask\frame\partition.py", line 99, in <lambda>
lambda df: pandas.DataFrame(df.iloc[row_indices, col_indices])
File "C:\Program Files (x86)\Microsoft Visual Studio\Shared\Python37_64\lib\site-packages\pandas\core\indexing.py", line 1762, in __getitem__
return self._getitem_tuple(key)
File "C:\Program Files (x86)\Microsoft Visual Studio\Shared\Python37_64\lib\site-packages\pandas\core\indexing.py", line 2067, in _getitem_tuple
self._has_valid_tuple(tup)
File "C:\Program Files (x86)\Microsoft Visual Studio\Shared\Python37_64\lib\site-packages\pandas\core\indexing.py", line 703, in _has_valid_tuple
self._validate_key(k, i)
File "C:\Program Files (x86)\Microsoft Visual Studio\Shared\Python37_64\lib\site-packages\pandas\core\indexing.py", line 2009, in _validate_key
raise IndexError("positional indexers are out-of-bounds")
IndexError: positional indexers are out-of-bounds

# Fixed code
def __getitem__(self, key):
    kwargs = self._kwargs.copy()
    # Most of time indexing DataFrameGroupBy results in another DataFrameGroupBy object unless circumstances are
    # special in which case SeriesGroupBy has to be returned. Such circumstances are when key equals to a single
    # column name and is not a list of column names or list of one column name.
    make_dataframe = True
    if self._drop and self._as_index:
        if not isinstance(key, list):
            key = [key]
            kwargs["squeeze"] = True
            make_dataframe = False
    # When `as_index` is False, pandas will always convert to a `DataFrame`, we
    # convert to a list here so that the result will be a `DataFrame`.
    elif not self._as_index and not isinstance(key, list):
        # Sometimes `__getitem__` doesn't only get the item, it also gets the `by`
        # column. This logic is here to ensure that we also get the `by` data so
        # that it is there for `as_index=False`.
        if (
            isinstance(self._by, type(self._query_compiler))
            and all(c in self._columns for c in self._by.columns)
            and self._drop
        ):
            key = list(self._by.columns) + [key]
        else:
            key = [key]
    if isinstance(key, list) and (make_dataframe or not self._as_index):
        return DataFrameGroupBy(
            self._df[key],
            self._by,
            self._axis,
            idx_name=self._idx_name,
            drop=self._drop,
            **kwargs,
        )
    return SeriesGroupBy(
        self._df[key],
        self._by,
        self._axis,
        idx_name=self._idx_name,
        drop=False,
        **kwargs,
    )