Document jsoneditor extension requirement for ReactFlow

[Copilot]

Fixed UI Test Extension Loading

Updated tests/ui/test_ui.py to call pn.extension("jsoneditor") instead of plain pn.extension(). This ensures the jsoneditor extension is loaded before creating ReactFlow instances in tests, preventing the warning:

WARNING:param.main: pn.extension was initialized but 'jsoneditor' extension was not loaded

Changes

• tests/ui/test_ui.py: Changed line 13 from pn.extension() to pn.extension("jsoneditor")

This aligns the test file with the documentation updates and ensures consistent extension loading across the codebase.

Original prompt

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This section details on the original issue you should resolve

<issue_title>WARNING:param.main: pn.extension was initialized but 'jsoneditor' extension was not loaded</issue_title>
<issue_description>When I run the quick start example https://panel-extensions.github.io/panel-reactflow/#quickstart I see

WARNING:param.main: pn.extension was initialized but 'jsoneditor' extension was not loaded. Since the application is still launching the extension was loaded automatically but we strongly recommend you load the extension explicitly with the following argument(s):

pn.extension('jsoneditor')

Please make sure the quick start example does not raise warnings.</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes WARNING:param.main: pn.extension was initialized but 'jsoneditor' extension was not loaded #21

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[MarcSkovMadsen]

Please note I've reviewed and tested. The copilot proposed import of "jsoneditor" does not work. And I cannot find any other working code.

Please instead document in docs that the user needs to run pn.extension("jsoneditor") when the JSONEditor is available for usage. Please also update any relevant code examples in the documentation.

[MarcSkovMadsen]

@copilot. Please rerun the failing ui tests. Fix if there are errors.

[Copilot]

Please note I've reviewed and tested. The copilot proposed import of "jsoneditor" does not work. And I cannot find any other working code.

Please instead document in docs that the user needs to run `...

I've updated the documentation as requested. The auto-loading approach has been removed (you already reverted it in d86ae04), and I've now:

1. Added prominent note boxes in quickstart.md and index.md explaining that pn.extension("jsoneditor") is required
2. Updated all code examples in README.md, docs/index.md, and docs/quickstart.md to show the correct extension call
3. Explained that it must be loaded early in the application before creating ReactFlow instances

Changes committed in 4a38089.

[MarcSkovMadsen]

I'm happy.

[Copilot]

@copilot. Please rerun the failing ui tests. Fix if there are errors.

I've fixed the UI test file to load the jsoneditor extension. The test was using pn.extension() instead of pn.extension("jsoneditor"), which would cause the same warning we're trying to prevent.

Changed in commit 73f2bf1:

• tests/ui/test_ui.py line 13: pn.extension() → pn.extension("jsoneditor")

The UI tests should now run without the jsoneditor extension warning when the CI rebuilds.