message: feat(TopBar): notify the user when reloading the schema fails
  It depends on state.unreachableEndpoint, also used when sending the introspection query
diff: @@ -768,11 +768,18 @@ export class GraphQLEditor extends React.PureComponent<
  )
  if (result) {
  const { schema } = result
  - this.setState({ schema, isReloadingSchema: false })
  + this.setState({
  + schema,
  + isReloadingSchema: false,
  + endpointUnreachable: false,
  + })
  this.renewStacks(schema)
  }
  } catch (e) {
  - this.setState({ isReloadingSchema: false })
  + this.setState({
  + isReloadingSchema: false,
  + endpointUnreachable: true,
  + })
  }
  }
  