Add error message for failing to join a room as a guest (which may or may not be because we're a guest: we can't tell)
Add error message for failing to join a room as a guest (which may or may not be because we're a guest: we can't tell)

matrix-org/matrix-react-sdk,matrix-org/matrix-react-sdk,aperezdc/matrix-react-sdk,matrix-org/matrix-react-sdk,aperezdc/matrix-react-sdk,matrix-org/matrix-react-sdk,aperezdc/matrix-react-sdk,aperezdc/matrix-react-sdk,matrix-org/matrix-react-sdk,matrix-org/matrix-react-sdk