Mapbox "fitBounds" handling

As per https://github.com/plotly/plotly.R/blob/9ee548023bba6d68dd953f46485b2e611026766b/inst/htmlwidgets/plotly.js#L206-L220

I believe the if(!args) check should be changed (or the parameter for args should default to null or some other calculated default, not {}) as it currently causes an "e is undefined" error in mapbox (where e is the 2nd parameter).

I've got around it by explicitly providing a mapbox = list(_fitBounds = list(c(xmin, ymin), c(xmax, ymax)), options = list()) entry in my plotly::layout call.

This also serves as a reminder that the fitBounds doesn't seem to work for restyle either.

從 inst/htmlwidgets/plotly.js 的第 206–220 行開始，重點關注 fitBounds 引數的預設值，以及產生第二個參數為 undefined 錯誤的 Mapbox 呼叫。分別在有和沒有明確 mapbox 選項清單的情況下重現此問題，然後驗證 fitBounds 在 restyle 期間也能正常運作。