message: Don't start block when in read-only mode
diff: @@ -877,6 +877,10 @@ fc::time_point producer_plugin_impl::calculate_pending_block_time() const {
  producer_plugin_impl::start_block_result producer_plugin_impl::start_block(bool &last_block) {
  chain::controller& chain = app().get_plugin<chain_plugin>().chain();
  +
  + if( chain.get_read_mode() == chain::db_read_mode::READ_ONLY )
  + return start_block_result::waiting;
  +
  const auto& hbs = chain.head_block_state();
  //Schedule for the next second's tick regardless of chain state
  