ft_get problem: when passing in ft_links output when bad urls

[sckott]

related crminer issue ropensci-archive/crminer#28

on cache-clean branch but should be broken on master as well:

res2 <- ft_search(query = 'ecology', from = 'crossref', limit = 3)
out <- ft_links(res2)
ft_get(x = out, type = "pdf")
#> Error in private$crul_h_pool[[z]] <- handle :
#>   wrong args for environment subassignment
#> In addition: Warning message:
#> In if (!grepl("https?://", x)) stop("Not a proper url") else x :
#>   the condition has length > 1 and only the first element will be used

[sckott]

there's two urls for a single article, each of which has unspecified type, so I think that's the problem is we're passing 2 urls to a function that expects 1