failf: remove newline from formatting strings

... as failf adds one itself.

Also: add an assert() to failf() that triggers on a newline in the
format string!

Closes #6365

1 files changed, 1 insertions, 1 deletions

diff --git a/lib/doh.c b/lib/doh.c
index c2b76de53..41d34dd30 100644
--- a/lib/doh.c
+++ b/lib/doh.c
@@ -225,7 +225,7 @@ static CURLcode dohprobe(struct Curl_easy *data,
   DOHcode d = doh_encode(host, dnstype, p->dohbuffer, sizeof(p->dohbuffer),
                          &p->dohlen);
   if(d) {
-    failf(data, "Failed to encode DOH packet [%d]\n", d);
+    failf(data, "Failed to encode DOH packet [%d]", d);
     return CURLE_OUT_OF_MEMORY;
   }