Environment data

• VS Code version: 1.58.0-insider
• Jupyter Extension version (available under the Extensions sidebar): v2021.7.978384885
• Python Extension version (available under the Extensions sidebar): v2021.7.969414671-dev
• OS (Windows | Mac | Linux distro) and version: Win 10.0.19043
• Python and/or Anaconda version: 3.9.0 64-bit
• Type of virtual environment used (N/A | venv | virtualenv | conda | ...): N/A
• Jupyter server running: Local

Expected behaviour

Plotly graphs are shown after re-opening a saved Jupyter notebook with these graphs

Actual behaviour

The ouput is blank after re-opening a notebook that contains cell output using the Plotly 'notebook' renderer. The graphs are shown correctly after re-executing the affected cells. Related to the fix for #6334 and merge #6318 with which support for the 'notebook' renderer was added.

Log output:

VM12:5 Uncaught TypeError: require.undef is not a function
    at <anonymous>:5:17
    at h (vscode-webview://f620ad82-e8b9-40f2-a1ab-808101a5c2a2/notebookWebviewPreloads.js:3)
    at vscode-webview://f620ad82-e8b9-40f2-a1ab-808101a5c2a2/notebookWebviewPreloads.js:3
resourceLoading.ts:82 Error: Unable to read file 'c:\Temp\plotly.js' (Error: Unable to resolve non-existing file 'c:\Temp\plotly.js')
    at ai.doReadFileStream (fileService.ts:539)
    at async Object.w [as loadLocalResource] (resourceLoading.ts:68)
    at async u.loadResource (baseWebviewElement.ts:530)
plotly.js:1 Failed to load resource: the server responded with a status of 404 ()
VM14:4 Registering custom require.js for Jupyter Kernel

The logs indicate that require.js is available only after the initial try to display the cell content which fails with 404.

Steps to reproduce:

import plotly.express as px
df = px.data.gapminder()
fig = px.scatter(df, x="gdpPercap", y="lifeExp", animation_frame="year", animation_group="country",
           size="pop", color="continent", hover_name="country",
           log_x=True, size_max=55, range_x=[100,100000], range_y=[25,90])
fig.show(renderer='notebook')

1. Run notebook confirming that graphs are working normal
2. Save notebook
3. Close and re-open notebook
4. Only blank cell output is shown where the graph should be
5. Re-running the notebook creates the graph again

Logs

XXX