闪亮的App: ggplot2将不会显示后的数据，错误:inccorect length()， expect ()

I am trying to build an R Shiny app that will display custom scatterplots. I let the user choose which variables from the dataset to place on the x and y axis with select boxes. Furthermore (this is where the trouble starts) I would like the ability to limit the range of values from each variable plotted in the graph by means of a custom slider for each selected variable. So, basically the user specifies a min and max value for each variable. I accomplish this with the I am trying to build an R Shiny app that will d