Allow fetching plugins from URL

[FabioRosado]

This PR adds the possibility to fetch javascript plugins from an URL and import it as a module.

As part of this, I reworked the robustFetch since I realised that fetch will throw a TypeError when trying to fetch from bad URLs like http://blah.blah and don't return a response. Robust fetch now throws a fetch error if fetch throws the TypeError.

It also killed the old handleFetchError since the error message is now being thrown in the robustFetch.

FetchErrors will now inherit from UserError, which will create the banner for us, so we don't have to do things like:

• handle fetch error
• throw user Error for banner

Plugins

new method created fetchUserPlugins which loops over the plugins list and calls either fetchJSPlugin or fetchPythonPlugin. Currently we are looking at the file extension in the url and calling the right fetch method, otherwise we will throw an exception.

For the JS plugins, they will only use the afterStartup lifecycle, which is probably fine. I've also added try/catch in the plugin manager, because my hello world plugin was failing with afterSetup is not a function unless I created a plugin that had all the Plugin methods but nothing in there.

We can't import the base Plugin class from pyscript because when we import the module we can't access the pyscript/plugin module.

There's a lot of rough edges but maybe it's okay for the first pass.

TODO

A few things still need to do:

• Create docs for fetching python plugins
• Create docs for fetching js docs
• Docs on the new Error Code
• Fix jest tests

[JeffersGlass]

Really good stuff! A handful of small changes/thoughts, and one larger one which is really a comment about register_custom_element and does it belong in the Plugin class at all...

[marimeireles]

Coolio!

[marimeireles]

if you want to use

if you want to learn how to use?

[FabioRosado]

Maybe I need to reword this, what i was trying to say was something along the lines of: "You can do stuff in python using pyscripts apis. But if you are comfortable using javascript you can do that to"

[JeffersGlass]

Hi @FabioRosado! Let me know if there's anything I can help with on this PR - I think it's swell and an awesome feature to add. 😃

If the only blocker is the Docs thought, we could wait for that to be a separate PR.

[FabioRosado]

Hi @FabioRosado! Let me know if there's anything I can help with on this PR - I think it's swell and an awesome feature to add. 😃

If the only blocker is the Docs thought, we could wait for that to be a separate PR.

Hey Jeff, just fixed the merge conflicts, yeah let's do the docs as a separate PR 😄 I'll try to knock it off over the weekend if I get the time thanks!

[JeffersGlass]

Sorry to took me awhile to get back around to this - thanks for all the adjustments and clarifications! We'll tackle the additional Plugin tutorial as a thought for the future.

LGTM!

[FabioRosado]

I didnt have time to write the docs yet but it's on my list 😄 thank you for the approval