message: minor type nit fix
diff: @@ -313,7 +313,7 @@ export default class PgClient {
  private async walkFilterFieldPath(
  enclosingCard: Card,
  path: string,
  - expression: Expression,
  + expression: CardExpression,
  handleLeafField: FilterFieldHandler<CardExpression>,
  handleCsField?: FilterCsFieldHandler<CardExpression>,
  handleInteriorField?: FilterFieldHandlerWithEntryAndExit<CardExpression>
  