Don't send rich text response when there is no console output
Don't send rich text response when there is no console output

When generating the rich text response to display an R object, first
check that there is console output. If the object would not be
displayed at the console then do not generate a response, so that the
notebook more closely mimics what would be displayed at the console.

elaOnMars/IRkernel,mikecroucher/IRkernel,Phobia0ptik/IRkernel,ChinaQuants/IRkernel,gdtm86/IRkernel,ibm-et/IRkernel,ibm-et/IRkernel,chendaniely/IRkernel