T-SQL: How to raise an error on a user defined function (udf)

A common programming task is to create a user-defined function. The function can perform some tasks and raise an error if some validation fails.
Let us try to raise an error

CREATE FUNCTION dbo.Division(@op1 INT, @op2 INT)
RETURNS INT
AS
BEGIN
    IF (@op2 = 0)
    BEGIN
    RAISERROR ('Division by zero.', 16, 1);
    END

    RETURN CAST(@op1 AS DECIMAL(18, 8)) /@op2
END

But this approach gives the following error:

Msg 443, Level 16, State 14, Procedure Division, Line 7 [Batch Start Line 0]
Invalid use of a side-effecting operator 'RAISERROR' within a function.

So another approach is needed.
Let us try the THROW statement

CREATE FUNCTION dbo.Division(@op1 INT, @op2 INT)
RETURNS INT
AS
BEGIN
    IF (@op2 = 0)
    BEGIN
    ;THROW 51000, 'Division by zero.',1;
    END

    RETURN CAST(@op1 AS DECIMAL(18, 8)) /@op2
END

But the result is the same as the RAISERROR:

Msg 443, Level 16, State 14, Procedure Division, Line 7 [Batch Start Line 0]
Invalid use of a side-effecting operator 'THROW' within a function.

Having tried all the known solutions to throw an exception in Sql Server, an alternative is needed.
Let's try a cast conversion error:

CREATE FUNCTION dbo.Division(@op1 INT, @op2 INT)
RETURNS DECIMAL(18, 8)
AS
BEGIN
    IF (@op2 = 0)
    BEGIN
    RETURN CAST('Division by zero.' AS INT);
    END

    RETURN CAST(@op1 AS DECIMAL(18, 8)) /  CAST(@op2 AS DECIMAL(18, 8))
END

The function is now created with success.
Let us see the result of calling the function with a division by zero:

SELECT dbo.Division(1, 0)

The following exception is thrown:

Msg 245, Level 16, State 1, Line 14
Conversion failed when converting the varchar value 'Division by zero.' to data type int.


It's not the ideal solution, but it allows us to generate a exception on a T-SQL function.