fix warning in api_test

Author: QuietMisdreavus

api_test/main.c

@@ -1179,7 +1179,7 @@ static void check_markdown_plaintext(test_batch_runner *runner, char *markdown)
   cmark_node *textNode = cmark_node_first_child(pg);
   INT_EQ(runner, cmark_node_get_type(textNode), CMARK_NODE_TEXT, "markdown '%s' did not produce a text node inside the paragraph node", markdown);
   const char *text = cmark_node_get_literal(textNode);
-  OK(runner, text, "Text literal for '%s' was null", markdown);
+  OK(runner, (text != NULL), "Text literal for '%s' was null", markdown);
   if (text) {
     STR_EQ(runner, text, markdown, "markdown '%s' resulted in '%s'", markdown, text);
   } else {