Why doesn't PHP catch a “Class not found” error?

Question

In the following example, if the class does not exist, I want to catch the error and create a Null class instead.

But in spite of my try/catch statement

Answer 1

php >= 7.0

php can catch 'class not found' as Throwable

try {
        return new $className($smartFormIdCode);
} catch (\Throwable $ex) {
        return new SmartFormNull($smartformIdCode);
}