wp-includes/SimplePie/src/SimplePie.php:1916Get the error message for the occurred error
string|array public function error() { return $this->error; }One change between 6.7.7 and 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
string|array to string|string[]|null.verified against sourcesrc/wp-includes/SimplePie/src/SimplePie.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.