Narrow return type & add param type for wp_json_encode() (#227)

* Narrow return typ & add param type for wp_json_encode()

* Fix cs issue

functionMap.php

@@ -188,6 +188,7 @@
     'wp_get_post_tags' => ["(\$post_id is 0 ? array{} : ((\$args is array{fields: 'names'|'slugs'} ? list<string> : (\$args is array{fields: 'id=>name'|'id=>slug'} ? array<int, string> : (\$args is array{fields: 'id=>parent'} ? array<int, int> : (\$args is array{fields: 'ids'|'tt_ids'} ? list<int> : (\$args is array{fields: 'count'} ? numeric-string : array<int, \WP_Term>)))))|\WP_Error))"],
     'wp_get_post_terms' => ["(\$post_id is 0 ? array{} : (\$taxonomy is empty ? array{} : ((\$args is array{fields: 'names'|'slugs'} ? list<string> : (\$args is array{fields: 'id=>name'|'id=>slug'} ? array<int, string> : (\$args is array{fields: 'id=>parent'} ? array<int, int> : (\$args is array{fields: 'ids'|'tt_ids'} ? list<int> : (\$args is array{fields: 'count'} ? numeric-string : array<int, \WP_Term>)))))|\WP_Error)))"],
     'wp_get_object_terms' => ["(\$object_ids is empty ? array{} : (\$taxonomies is empty ? array{} : ((\$args is array{fields: 'names'|'slugs'} ? list<string> : (\$args is array{fields: 'id=>name'|'id=>slug'} ? array<int, string> : (\$args is array{fields: 'id=>parent'} ? array<int, int> : (\$args is array{fields: 'ids'|'tt_ids'} ? list<int> : (\$args is array{fields: 'count'} ? numeric-string : array<int, \WP_Term>)))))|\WP_Error)))"],
+    'wp_json_encode' => ['non-empty-string|false', 'depth' => 'positive-int'],
     'wp_parse_list' => ['($input_list is array ? array<scalar> : list<string>)'],
     'wp_parse_str' => [null, '@phpstan-param-out' => 'array<int|string, array|string> $result'],
     'size_format' => ["(\$bytes is not numeric ? false : (\$bytes is negative-int|'0' ? false : string))"],

wordpress-stubs.php

@@ -108899,6 +108899,8 @@ function _wp_die_process_input($message, $title = '', $args = array())
      * @param int   $depth Optional. Maximum depth to walk through $value. Must be
      *                     greater than 0. Default 512.
      * @return string|false The JSON encoded string, or false if it cannot be encoded.
+     * @phpstan-param positive-int $depth
+     * @phpstan-return non-empty-string|false
      */
     function wp_json_encode($value, $flags = 0, $depth = 512)
     {