Unable to print EXPLAIN

[konjac]

Describe the bug
EXPLAIN statement could not be printed with the following error.

Exception: Internal error: Unsupported logical plan: Explain must be root of the plan.
This was likely caused by a bug in DataFusion's code and we would welcome that you file an bug report in our issue tracker

To Reproduce
Steps to reproduce the behavior:

>>> from datafusion import SessionContext
>>> ctx = SessionContext()
>>> ctx.sql("explain select 1")
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/kuhuan/.local/lib/python3.10/site-packages/datafusion/dataframe.py", line 71, in __repr__
    return self.df.__repr__()
Exception: Internal error: Unsupported logical plan: Explain must be root of the plan.
This was likely caused by a bug in DataFusion's code and we would welcome that you file an bug report in our issue tracker

Expected behavior
The output should just be like using explain function

>>> ctx.sql("select 1").explain()
DataFrame()
+---------------+--------------------------------------+
| plan_type     | plan                                 |
+---------------+--------------------------------------+
| logical_plan  | Projection: Int64(1)                 |
|               |   EmptyRelation                      |
| physical_plan | ProjectionExec: expr=[1 as Int64(1)] |
|               |   PlaceholderRowExec                 |
|               |                                      |
+---------------+--------------------------------------+

Additional context
Add any other context about the problem here.