How to forbid passing empty arguments to a procedure?

Question

Oracle

How, when creating a pl / sql procedure, to prohibit passing NULL values ​​to arguments, to make them strictly (for example) VARCHAR2? At the same time, it is desirable to avoid explicit checks in the style of "IF arg IS NULL THEN ...", because many arguments are passed and their separate check clogs the code. Is there something like an argument modifier that says what values ​​can be passed?
For example, this code runs without errors, but I want NULL to be treated as an invalid argument.

DECLARE
 PROCEDURE null_args_testing(arg IN VARCHAR2) IS
  BEGIN 
   NULL;
  END;
BEGIN 
 null_args_testing('STRING'); -- При таком вызове процедура должна работать
 null_args_testing(NULL); -- при таком вызове должно происходить исключение
END;

Answer 1

docs.oracle.com (Parameter Declaration):

You cannot constrain this data type (with NOT NULL, for example).

Answer 2

The first value in raise_application_error- must be in the custom error range:
PROCEDURE null_args_testing(arg IN VARCHAR2) IS
BEGIN
if arg is null then
raise_application_error(-20101, 'Value cannot be NULL');
end if;
NULL;
END;
You can also do this if you need more complex logic:
PROCEDURE null_args_testing(arg IN VARCHAR2) IS
p_is_null exception;
BEGIN
if arg is null then
raise p_is_null;
end if;
exception
when p_is_null then
/*processing logic*/
raise;/*procedure ends*/
END;