What potential pitfalls should developers be aware of when using interfaces in PHP?

One potential pitfall when using interfaces in PHP is not implementing all the methods defined in the interface, which can lead to fatal errors at runtime. To avoid this issue, developers should ensure that all methods in the interface are implemented in the class that is implementing the interface.

interface Logger {
    public function log($message);
    public function error($message);
}

class FileLogger implements Logger {
    public function log($message) {
        // log message to file
    }

    public function error($message) {
        // log error message to file
    }
}