issue computing repr of `Figure`

Chưa có ai nhận issue này.

Due to https://github.com/matplotlib/matplotlib/pull/10292 during a save operation we temporarily remove the manager

```python
%matplotlib widget
import matplotlib.pyplot as plt
plt.plot(range(5))
fig = plt.gcf()

## new cell
fig
```

and you will get a traceback that looks like:

```pytb
---------------------------------------------------------------------------
AttributeError Traceback (most recent call last)
~/.virtualenvs/bleeding/lib/python3.9/site-packages/IPython/core/formatters.py in __call__(self, obj)
339 pass
340 else:
--> 341 return printer(obj)
342 # Finally look for special method names
343 method = get_real_method(obj, self.print_method)

~/.virtualenvs/bleeding/lib/python3.9/site-packages/IPython/core/pylabtools.py in (fig)
242
243 if 'png' in formats:
--> 244 png_formatter.for_type(Figure, lambda fig: print_figure(fig, 'png', **kwargs))
245 if 'retina' in formats or 'png2x' in formats:
246 png_formatter.for_type(Figure, lambda fig: retina_figure(fig, **kwargs))

~/.virtualenvs/bleeding/lib/python3.9/site-packages/IPython/core/pylabtools.py in print_figure(fig, fmt, bbox_inches, **kwargs)
126
127 bytes_io = BytesIO()
--> 128 fig.canvas.print_figure(bytes_io, **kw)
129 data = bytes_io.getvalue()
130 if fmt == 'svg':

~/source/p/mpl-master/lib/matplotlib/backend_bases.py in print_figure(self, filename, dpi, facecolor, edgecolor, orientation, format, bbox_inches, **kwargs)
2058 if bbox_inches:
2059 if bbox_inches == "tight":
-> 2060 renderer = _get_renderer(
2061 self.figure,
2062 functools.partial(

~/source/p/mpl-master/lib/matplotlib/backend_bases.py in _get_renderer(figure, print_method)
1546 with cbook._setattr_cm(figure, draw=_draw):
1547 try:
-> 1548 print_method(io.BytesIO())
1549 except Done as exc:
1550 figure._cachedRenderer, = exc.args

~/source/p/mpl-master/lib/matplotlib/backends/backend_agg.py in print_png(self, filename_or_obj, metadata, pil_kwargs, *args, **kwargs)
533
534 else:
--> 535 FigureCanvasAgg.draw(self)
536 renderer = self.get_renderer()
537 with cbook._setattr_cm(renderer, dpi=self.figure.dpi), \

~/source/p/mpl-master/lib/matplotlib/backends/backend_agg.py in draw(self)
391 self.renderer = self.get_renderer(cleared=True)
392 # Acquire a lock on the shared font cache.
--> 393 with RendererAgg.lock, \
394 (self.toolbar._wait_cursor_for_draw_cm() if self.toolbar
395 else nullcontext()):

~/source/other_source/cpython/Lib/contextlib.py in __enter__(self)
111 del self.args, self.kwds, self.func
112 try:
--> 113 return next(self.gen)
114 except StopIteration:
115 raise RuntimeError("generator didn't yield") from None

~/source/p/mpl-master/lib/matplotlib/backend_bases.py in _wait_cursor_for_draw_cm(self)
2732 if self._draw_time - last_draw_time > 1:
2733 try:
-> 2734 self.set_cursor(cursors.WAIT)
2735 yield
2736 finally:

~/source/p/mpl-master/lib/matplotlib/backends/backend_webagg_core.py in set_cursor(self, cursor)
379 def set_cursor(self, cursor):
380 if cursor != self.cursor:
--> 381 self.canvas.send_event("cursor", cursor=cursor)
382 self.cursor = cursor
383

~/source/p/mpl-master/lib/matplotlib/backends/backend_webagg_core.py in send_event(self, event_type, **kwargs)
344
345 def send_event(self, event_type, **kwargs):
--> 346 self.manager._send_event(event_type, **kwargs)
347
348

AttributeError: 'NoneType' object has no attribute '_send_event'
```

I thought we should be going through https://github.com/matplotlib/matplotlib/blob/59b5e0e873dd3420758498c90b15f7f70cb007da/lib/matplotlib/figure.py#L403-L408 but it looks like we are going trough a lambda from IPython core....

I think this could legitimately go against IPython, Matplotlib, or here. Leaving here as the "middle ground" ;)

Tái hiện traceback trong một notebook bằng `%matplotlib widget`, sau đó kiểm tra đường dẫn repr của Figure trong figure.py quanh các dòng 403-408, lambda formatter của IPython pylabtools và backend_webagg_core.py quanh set_cursor và send_event. Được xem là hoàn tất khi `fig` được hiển thị sau khi việc vẽ hoàn tất mà không xảy ra AttributeError liên quan đến manager trong quá trình render.

Do mô hình lập chỉ mục viết ra từ nội dung của issue.