More precise emit_int error handling

Signed-off-by: Emerson Knapp <emerson.b.knapp@gmail.com>

rcl/src/rcl/type_version_hash.c

@@ -71,10 +71,15 @@ static int emit_key(yaml_emitter_t * emitter, const char * key)
 
 static int emit_int(yaml_emitter_t * emitter, size_t val, const char * fmt)
 {
-  // longest uint64 is 21 decimal digits
+  // longest uint64 is 20 decimal digits, plus one byte for trailing \0
   char decimal_buf[21];
   yaml_event_t event;
-  if ((size_t)snprintf(decimal_buf, sizeof(decimal_buf), fmt, val) >= sizeof(decimal_buf)) {
+  int ret = snprintf(decimal_buf, sizeof(decimal_buf), fmt, val);
+  if (ret < 0) {
+    emitter->problem = "Failed expanding integer";
+    return 0;
+  }
+  if ((size_t)ret >= sizeof(decimal_buf)) {
     emitter->problem = "Decimal buffer overflow";
     return 0;
   }