Message Oracle PLS-00218 - a variable declared NOT NULL must have an initialization assignment

ERRORa variable declared NOT NULL must have an initialization assignment
CAUSEIn general, variables that have no initialization clause in their declaration are automatically initialized to NULL. This is illogical for NOT NULL variables; therefore, an initialization clause is required.
ACTIONAdd an initialization clause to the variable declaration. If the initilization is too complicated for the syntax, one can add a function call (in a later release).