The function nchar is not supported with natively compiled modules

Question

Error : The function nchar is not supported with natively compiled modules.

How I can use Nchar() Function in native Function?

my query is :

Declare @Input NVARCHAR(MAX)
DECLARE @Output NVARCHAR(MAX)=N''
DECLARE @i INT
DECLARE @C NVARCHAR(1)

SET @i=0
SET @C=SUBSTRING(@Input,@i,1)

While  @C Not IN (
        NCHAR(0x060C), -- Arabic Comma
        NCHAR(0x061B) -- Arabic Semicolon
        )
Begin 
    SET @Output=@Output+@C
End