_wp_json_convert_string type mismatch: returns string on success; false on failure

[hellofromTonya]

The private function _wp_json_convert_string (which converts a string to UTF-8) also returns false, though its @return specifies only string.

How? ​`mb_convert_encoding` returns a string on success and a false on failure.

Is this a bug or docs fix? It's both.

Reviewing its context, it's used by _wp_json_sanity_check to convert IDs and data value. The IDs are the problem. How so? Each ID is used as either a key or project for referencing the data value.

What happens if the conversion to UTF-8 fails? The key or property would either be an empty string or false. That's problematic as it can cause unexpected JSON encoding results.

For example, this ​3v4l snippet simulates the convert encoding failure to view the results through the JSON encoding process. Notice how the returned JSON is invalid when it fails. (Note: This snippet is forcing a failure.)

[desrosj]

#57172 was marked as a duplicate.