check_content_type() should correctly error when response has no content_type but suffix is checked.

[cderv]

This is issue is the same error as #277 but in its minimal form.

I stumbled upon this error while trying to do some mocking in testing with httr2::response().

> httr2::resp_body_json(httr2::response())
Error in `if (!is.null(suffix) && endsWith(content_type, suffix)) ...`:
! missing value where TRUE/FALSE needed
Run `rlang::last_trace()` to see where the error occurred.
> rlang::last_trace()
<error/rlang_error>
Error in `if (!is.null(suffix) && endsWith(content_type, suffix)) ...`:
! missing value where TRUE/FALSE needed
---
Backtrace:
    ▆
 1. └─httr2::resp_body_json(httr2::response())
 2.   └─httr2:::check_content_type(...)

I don't think the error is very clear to understand is the call is really allowed or not.

Simpler reprex:

httr2:::check_content_type(httr2::response(), "application/json", suffix = "+json")

In there,

httr2/R/resp-body.R

Lines 130 to 138 in 7962bcd

	content_type <- resp_content_type(resp)
	if (content_type %in% types) {
	return()
	}
	# https://datatracker.ietf.org/doc/html/rfc6838#section-4.2.8
	if (!is.null(suffix) && endsWith(content_type, suffix)) {
	return()
	}

content_type can be NA_character_

httr2/R/resp-headers.R

Lines 101 to 107 in d789827

	resp_content_type <- function(resp) {
	if (resp_header_exists(resp, "content-type")) {
	parse_media(resp_header(resp, "content-type"))$type
	} else {
	NA_character_
	}
	}

and this will make endsWith() returns a NA

endsWith(NA_character_, "+json")
#> [1] NA

which is not good in the if() call and with &&

#277 was fixed by #278 but regarding the specific cache usage.

I believe here the error should be clearer. Maybe is.na(content_types) should be checked also when !is.null(suffix) to handle this specific content_types value, and throw useful error.

[hadley]

Looks like this is fixed in #262:

Error in `httr2::resp_body_json()`:
! Unexpected content type "NA"
• Expecting type "application/json", or suffix "json"