Bail from get_term() if a filter returns an object that is not a WP_Term.

This prevents fatal errors in certain cases.

Props tmuikku.
Fixes #35808.

git-svn-id: https://develop.svn.wordpress.org/trunk@36516 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-includes/taxonomy.php

@@ -857,6 +857,11 @@ function get_term( $term, $taxonomy = '', $output = OBJECT, $filter = 'raw' ) {
 	 */
 	$_term = apply_filters( "get_$taxonomy", $_term, $taxonomy );
 
+	// Bail if a filter callback has changed the type of the `$_term` object.
+	if ( ! ( $_term instanceof WP_Term ) ) {
+		return $_term;
+	}
+
 	// Sanitize term, according to the specified filter.
 	$_term->filter( $filter );