PHP error when using fwrite()

We’ve been seeing this fatal error, possibly since updating to PHP 8 when using th helpful plugin. Perhaps it does not have permissions to write?

TypeError: Caught TypeError (500): fwrite(): Argument #1 ($stream) must be of type resource, bool given in /plugins/helpful/core/solutions/class-wpml.php:76

I believe the error this thrown from:
Helpful\Core\Solutions\WPML->create_translation_file()