Plotly attributes/mode warning in Shiny

I am including a secondary y axis/bar chart coincident with a plotly scatterplot, and am getting the following warning:

“Warning: ‘bar’ objects don’t have these attributes: ‘mode’
Valid attributes include: ‘type’,‘visible’,…”

The chart seems to render correctly using the following code:

                 pmn_now <- plot_ly(file1_sub,x = ~year, y = ~get(input$outcome), name=ylabel, type= "scatter", 
                                               mode=("lines+markers"),marker=list( line =list(color="blue"))) %>%
                        add_trace(x=~year, y=~n_total, type="bar", yaxis="y2", opacity=0.35, 
                                       name="Number Total",marker = list(color="orange")) %>%
                           xaxis = list(title="Title 1",titlefont=list(size=14),tickangle=45),
                           yaxis = list(title=ylabel,titlefont=list(size=14),tickangle=0,dtick=.1,gridcolor="blue"),
                           yaxis2 = list(title="Number", overlaying ="y", 
                           title = titletext) 
                           legend = list(x = 0, y = 0.9, box.lty=0)


Given that the plot has the desired appearance and the code aligns with other examples I’ve seen, could someone identify the issue and suggest a solution?