Ignore error when importing JSON files in R - r

Question

I have this for loop that download a json file from a solr search server.
It loops over a vector that contain keywords (100, in this case):
library(jsonlite)
for (i in 1:100) {
docs <- fromJSON(paste("http://myurl.com/solr/select?df=topic&fq=",keywords[i],"&indent=on&q=*:*&rows=1&wt=json",sep=""))
numFound <- docs$response$numFound
print(numFound)
}
It works fine, until it reaches a certain keyword that is not found on the solr, and returns this error:
Error in open.connection(con, "rb") : HTTP error 400.
And then the loop stops.
Is there a way to ignore the error and proceed the loop?
I've read something using tryCatch but still couldn't figure it out.

Answer 1

Simpler than tryCatch, you can use the function try inside your keyword loop. This will attempt to load the URL, but if an error is encountered will print the error but continue to the next keyword.
library(jsonlite)
for (i in 1:100) {
try({
docs <- fromJSON(paste("http://myurl.com/solr/select?df=topic&fq=",keywords[i],"&indent=on&q=*:*&rows=1&wt=json",sep=""))
numFound <- docs$response$numFound
print(numFound)
})
}
If you also don't want to have the errors printed, specify silent = TRUE:
library(jsonlite)
for (i in 1:100) {
try({
docs <- fromJSON(paste("http://myurl.com/solr/select?df=topic&fq=",keywords[i],"&indent=on&q=*:*&rows=1&wt=json",sep=""))
numFound <- docs$response$numFound
print(numFound)
}, silent = TRUE)
}

Answer 2

I'm partial to purrr's safely for this kind of task, which works well in purrr's map functions. You can test it by getting JSONs from GitHub's API:
keywords <- c("hadley", "gershomtripp", "lsjdflkaj")
url <- "https://api.github.com/users/{.}/repos"
Now we can get the JSONs and extract the repo IDs
library(jsonlite)
library(purrr)
library(glue)
json_list <- map(keywords, safely(~ fromJSON(glue(url)) %>% .$id))
This will return a list of elements containing result and error. If there was an error it will be saved in error, otherwise the results will be save in result.
[[1]]
[[1]]$result
[1] 40423928 40544418 14984909 12241750 5154874 9324319 20228011 82348 888200 3116998
[11] 8296284 137344416 133734429 2788278 28724058 9470424 116708612 34325557 41144 41157
[21] 78543290 66588778 35225488 14507273 15718805 18562209 12522 115742443 119107571 201908
[[1]]$error
NULL
[[2]]
[[2]]$result
[1] 150995700 141743224 127107806 130802586 185857872 131488780 148619375 165221804 135417803 127116088
[11] 181662388 173351888 127131146 136896011
[[2]]$error
NULL
[[3]]
[[3]]$result
NULL
[[3]]$error
<simpleError in open.connection(con, "rb"): HTTP error 404.>