Publishing shiny app to connect: Warning: Error in pngfun: X11 is not available

I have a shiny app that works fine on RStudio Pro. When I try to publish it to RStudio Connect I get a "Warning: Error in pngfun: X11 is not available" error.

I realize I don't have the X11 capabilities on the Connect server, however I'm using the options(bitmapType='cairo') comment in my code. Shouldn't it be trying to use Cairo instead of X11 then?

Any ideas of how I can get around this problem?

Here's capabilities() from the Connect server:

capabilities()
jpeg png tiff tcltk X11 aqua
TRUE TRUE TRUE TRUE FALSE FALSE
http/ftp sockets libxml fifo cledit iconv
TRUE TRUE TRUE TRUE TRUE TRUE
NLS profmem cairo ICU long.double libcurl
TRUE FALSE TRUE TRUE TRUE TRUE

Thanks.