config modeBarButtonsToRemove fails if length is 1

The plot silently fails to render and throws a javascript error when listing only 1 button for removal with config(modeBarButtonsToRemove = c(...))

# Basic failure
plot_ly(data = mtcars, x = ~mpg, y = ~wt) %>%
  config(modeBarButtonsToRemove = c("hoverCompareCartesian"))

plot_ly(data = mtcars, x = ~mpg, y = ~wt) %>%
  config(modeBarButtonsToRemove = c("zoom2d"))

# Fails even when button is superfluous ("zoom3d" not needed for a 2d plot)
plot_ly(data = mtcars, x = ~mpg, y = ~wt) %>%
  config(modeBarButtonsToRemove = c("zoom3d"))

# Fails when passed as a scalar
plot_ly(data = mtcars, x = ~mpg, y = ~wt) %>%
  config(modeBarButtonsToRemove = "hoverCompareCartesian")

// javscript error from browser
 Uncaught TypeError: x.config.modeBarButtonsToRemove.push is not a function
    at Object.renderValue (plotly.js:155)
    at exports.OutputBinding.shinyBinding.renderValue (htmlwidgets.js:516)
    at exports.OutputBinding.onValueChange (output_binding.js:16)
    at exports.OutputBinding.delegator.(:7541/anonymous function) [as onValueChange] (http://127.0.0.1:7541/htmlwidgets-1.3/htmlwidgets.js:112:23)
    at OutputBindingAdapter.onValueChange (output_binding_adapter.js:21)
    at ShinyApp.receiveOutput (shinyapp.js:332)
    at ShinyApp.<anonymous> (shinyapp.js:544)
    at ShinyApp._sendMessagesToHandlers (shinyapp.js:529)
    at ShinyApp.dispatchMessage (shinyapp.js:515)
    at WebSocket.c.onmessage (shinyapp.js:112)
renderValue @ plotly.js:155
shinyBinding.renderValue @ htmlwidgets.js:516
onValueChange @ output_binding.js:16
delegator.(anonymous function) @ htmlwidgets.js:112
onValueChange @ output_binding_adapter.js:21
receiveOutput @ shinyapp.js:332
(anonymous) @ shinyapp.js:544
_sendMessagesToHandlers @ shinyapp.js:529
dispatchMessage @ shinyapp.js:515
c.onmessage @ shinyapp.js:112

Adding a second, even irrelevant value, fixes the error.

# Remove 2 buttons
plot_ly(data = mtcars, x = ~mpg, y = ~wt) %>%
  config(modeBarButtonsToRemove = c("hoverCompareCartesian","zoom2d"))

# zoom3d would not appear by default because this is a 2d plot, but adding it to the argument prevents the error
plot_ly(data = mtcars, x = ~mpg, y = ~wt) %>%
  config(modeBarButtonsToRemove = c("hoverCompareCartesian","zoom3d"))

I am using plotly 4.8.0

Reproduce the failure with the R examples using one-element and scalar modeBarButtonsToRemove values. Start at the plotly.js renderValue entry point shown in the browser stack trace, then verify that single-button configurations render without errors while the existing multi-button behavior remains intact.