message: feat: distinguish when messages are being loaded
diff: @@ -141,10 +141,12 @@ export function AllMessages({uri: uri0}: { uri: DocumentUri }) {
  )
  }
  +/** We factor out the body of {@link AllMessages} which lazily fetches its contents only when expanded. */
  function AllMessagesBody({uri, messages}: {uri: DocumentUri, messages: () => Promise<InteractiveDiagnostic[]>}) {
  - const [msgs, setMsgs] = React.useState<InteractiveDiagnostic[]>([])
  + const [msgs, setMsgs] = React.useState<InteractiveDiagnostic[] | undefined>(undefined)
  React.useEffect(() => void messages().then(setMsgs), [messages])
  - return <MessagesList uri={uri} messages={msgs}/>
  + if (msgs === undefined) return <>Loading messages..</>
  + else return <MessagesList uri={uri} messages={msgs}/>
  }
  /**
  