Salary Amount Fast Formula Compilation Error

Summary:

Fast Formula for getting Salary Amount is giving compilation error saying: the assignment uses inconsistent data types

Content (please ensure you mask any confidential information):

I have been working on a simple Fast Formula to get the Salary Amount based upon Payroll Frequency of an employee. If the employee is Salaried(S), the salary amount should be what extract attribute is bringing over, but if the Payroll Frequency is Hourly(H), then the salary_amount should be multiplied with generic working hours i.e. 2080.

But, when I am trying to compile the formula I am getting compilation error saying: Formula CRUNV_GET_SALARY_INFO, line 23, the assignment uses inconsistent data types.