# Buggy code
def __setitem__(self, key, value):
    if not isinstance(key, str):

        def setitem_without_string_columns(df):
            # Arrow makes memory-mapped objects immutable, so copy will allow them
            # to be mutable again.
            df = df.copy(True)
            df[key] = value
            return df

        return self._update_inplace(
            self._default_to_pandas(setitem_without_string_columns)._query_compiler
        )
    if is_list_like(value):
        if isinstance(value, (pandas.DataFrame, DataFrame)):
            if value.shape[1] != 1 and key not in self.columns:
                raise ValueError(
                    "Wrong number of items passed %i, placement implies 1"
                    % value.shape[1]
                )
            value = value[value.columns[0]].values
        elif isinstance(value, np.ndarray):
            if len(value.shape) > 1 and value.shape[1] != 1 and key not in self.columns:
                raise ValueError(
                    "Wrong number of items passed %i, placement implies 1"
                    % value.shape[1]
                )
            assert len(value.shape) < 3, (
                "Shape of new values must be compatible with manager shape"
            )
            value = value.T.reshape(-1)
            if len(self) > 0:
                value = value[: len(self)]
        if not isinstance(value, Series):
            value = list(value)
    if key not in self.columns:
        if isinstance(value, Series):
            if len(self.columns) == 0:
                self._query_compiler = value._query_compiler.copy()
            else:
                self._create_or_update_from_compiler(
                    self._query_compiler.concat(1, value._query_compiler),
                    inplace=True,
                )
            # Now that the data is appended, we need to update the column name for
            # that column to `key`, otherwise the name could be incorrect. Drop the
            # last column name from the list (the appended value's name and append
            # the new name.
            self.columns = self.columns[:-1].append(pandas.Index([key]))
        else:
            self.insert(loc=len(self.columns), column=key, value=value)
    elif len(self.index) == 0:
        new_self = DataFrame({key: value}, columns=self.columns)
        self._update_inplace(new_self._query_compiler)
    else:
        if isinstance(value, Series):
            value = value._query_compiler
        self._update_inplace(self._query_compiler.setitem(0, key, value))


# Traceback (ValueError)
Traceback (most recent call last):
File "/nfs/site/home/gashiman/.local/lib/python3.7/site-packages/pandas/core/frame.py", line 3054, in _ensure_valid_index
value = Series(value)
File "/nfs/site/home/gashiman/.local/lib/python3.7/site-packages/pandas/core/series.py", line 256, in __init__
data, index = self._init_dict(data, index, dtype)
File "/nfs/site/home/gashiman/.local/lib/python3.7/site-packages/pandas/core/series.py", line 334, in _init_dict
if data:
File "/localdisk/gashiman/modin/modin/pandas/base.py", line 3343, in __nonzero__
self.__class__.__name__
ValueError: The truth value of a Series is ambiguous. Use a.empty, a.bool(), a.item(), a.any() or a.all().

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
File "test_setitem.py", line 5, in <module>
df[0] = se
File "/localdisk/gashiman/modin/modin/pandas/dataframe.py", line 2072, in __setitem__
self._default_to_pandas(setitem_without_string_columns)._query_compiler
File "/localdisk/gashiman/modin/modin/pandas/base.py", line 245, in _default_to_pandas
result = op(pandas_obj, *args, **kwargs)
File "/localdisk/gashiman/modin/modin/pandas/dataframe.py", line 2068, in setitem_without_string_columns
df[key] = value
File "/nfs/site/home/gashiman/.local/lib/python3.7/site-packages/pandas/core/frame.py", line 2938, in __setitem__
self._set_item(key, value)
File "/nfs/site/home/gashiman/.local/lib/python3.7/site-packages/pandas/core/frame.py", line 2999, in _set_item
self._ensure_valid_index(value)
File "/nfs/site/home/gashiman/.local/lib/python3.7/site-packages/pandas/core/frame.py", line 3057, in _ensure_valid_index
"Cannot set a frame with no defined index "
ValueError: Cannot set a frame with no defined index and a value that cannot be converted to a Series

# Fixed code
def __setitem__(self, key, value):
    if key not in self.columns:
        # Handle new column case first
        if isinstance(value, Series):
            if len(self.columns) == 0:
                self._query_compiler = value._query_compiler.copy()
            else:
                self._create_or_update_from_compiler(
                    self._query_compiler.concat(1, value._query_compiler),
                    inplace=True,
                )
            # Now that the data is appended, we need to update the column name for
            # that column to `key`, otherwise the name could be incorrect. Drop the
            # last column name from the list (the appended value's name and append
            # the new name.
            self.columns = self.columns[:-1].append(pandas.Index([key]))
        elif (
            isinstance(value, np.ndarray)
            and len(value.shape) > 1
            and value.shape[1] != 1
        ):
            raise ValueError(
                "Wrong number of items passed %i, placement implies 1" % value.shape[1]
            )
        elif isinstance(value, (pandas.DataFrame, DataFrame)) and value.shape[1] != 1:
            raise ValueError(
                "Wrong number of items passed %i, placement implies 1" % value.shape[1]
            )
        else:
            self.insert(loc=len(self.columns), column=key, value=value)
        return

    if not isinstance(key, str):

        def setitem_without_string_columns(df):
            # Arrow makes memory-mapped objects immutable, so copy will allow them
            # to be mutable again.
            df = df.copy(True)
            df[key] = value
            return df

        return self._update_inplace(
            self._default_to_pandas(setitem_without_string_columns)._query_compiler
        )
    if is_list_like(value):
        if isinstance(value, (pandas.DataFrame, DataFrame)):
            value = value[value.columns[0]].values
        elif isinstance(value, np.ndarray):
            assert len(value.shape) < 3, (
                "Shape of new values must be compatible with manager shape"
            )
            value = value.T.reshape(-1)
            if len(self) > 0:
                value = value[: len(self)]
        if not isinstance(value, Series):
            value = list(value)

    if len(self.index) == 0:
        new_self = DataFrame({key: value}, columns=self.columns)
        self._update_inplace(new_self._query_compiler)
    else:
        if isinstance(value, Series):
            value = value._query_compiler
        self._update_inplace(self._query_compiler.setitem(0, key, value))