Errors are not handled on extension load

[nwmac]

Internal reference: SURE-9597

We don't handle errors during plugin load, so if you try and load a Vue 2 extension into Vue 3, the UI breaks.

We rely on correctly annotated extensions to avoid this situation, but we should look to see if we can improve the error handling.

For QA: Dev testing should be adequate, just install an extension and verify that it loads correctly.