Error handling with tryCatch

###Function for automatic error handling while downloading Facebook pages, posts, comments and replies with Rfacebook library###
### The code was developed as part of the Ancient Identities in Modern Britain (IARH) project
### Project: Ancient Identities in Modern Britain (IARH); ancientidentities.org
### Author: Marta Krzyzanska

###Requires defining variables:

limitError <-"(#17) User request limit reached"
unexpectedError<-"An unexpected error has occurred. Please retry your request later."

###Requires libraries:

library(Rfacebook)
library(devtools)
library(xlsx)

handleAPIErrors <- function(id,token,type,n){
	z=1
	y=2
	while(z<y){
		z=z+1
		content<-
		tryCatch(

		if(type=="pages"){
		searchPages(string=id, token=token, n=n)}
	
		else if(type=="posts"){
		getPage(page=id, token=token, n=n)}

		else if(type=="comments"){
		getPost(post=id,n=n,token=token)}

		else if(type=="replies"){
		getCommentReplies(id,n=n,token=token)}

		,
		error=function(error_message){
			message(error_message)
			error_message<-append(error_message,id)
			if(error_message$message==limitError){
                		Sys.sleep(900)
				return (1)
			}else if(error_message$message==unexpectedError){
			return (1)}else{
			return(error_message)
			z=y}
		}
		)
		if(class(content)=="numeric"){
		z=1}
	}
	return (content)
}