Blank canvas, no image data

[flsmith]

When trying to draw anything using ipycanvas in JupyterLab, I'm getting a blank canvas displayed and no image data being stored even with sync_image_data = True. I'm not using Voila here, though the blank canvas display looks similar to #342 and I've tried the solution there.

import numpy as np
from ipycanvas import Canvas

canvas = Canvas(width=200, height=200, sync_image_data = True)

canvas.fill_rect(25, 25, 100, 100)
canvas.clear_rect(45, 45, 60, 60)
canvas.stroke_rect(50, 50, 50, 50)

canvas.get_image_data()

---------------------------------------------------------------------------
RuntimeError                              Traceback (most recent call last)
Cell In[8], line 10
      7 canvas.clear_rect(45, 45, 60, 60)
      8 canvas.stroke_rect(50, 50, 50, 50)
---> 10 canvas.get_image_data()

File [/opt/conda/lib/python3.11/site-packages/ipycanvas/canvas.py:444](https://teachinghub.st-andrews.ac.uk/opt/conda/lib/python3.11/site-packages/ipycanvas/canvas.py#line=443), in _CanvasBase.get_image_data(self, x, y, width, height)
    435 """Return a NumPy array representing the underlying pixel data for a specified portion of the canvas.
    436 
    437 This will throw an error if there is no ``image_data`` to retrieve, this happens when nothing was drawn yet or
   (...)
    441 are (``x + width``, ``y + height``).
    442 """
    443 if self.image_data is None:
--> 444     raise RuntimeError(
    445         "No image data, please be sure that ``sync_image_data`` is set to True"
    446     )
    448 x = int(x)
    449 y = int(y)

RuntimeError: No image data, please be sure that ``sync_image_data`` is set to True

Versions are as follows:

Jupyterlab 4.2.0
ipycanvas 0.13.3
ipywidgets 8.1.2

Any help appreciated, and I'm happy to help get more details.

[flsmith]

This was caused by a version difference with the labextension which had previously been installed to ~/.local for some reason; apologies for the false report.