When I use this function in a worksheet (referencing a cell that contains no
spaces), it returns "Is Error" as it should

=IF(ISERROR(LEFT(TRIM(A3),FIND(" ",TRIM(A3)-1))),"Is Error","Is Not Error")

However when I use the VBA version, it throws an Error 1004, "Unable to get
the Find property of the WorksheetFunction class".

If Not IsError(Application.WorksheetFunction.Find(" ",
Trim(ActiveCell.Offset(0, -1)))) Then

I'm trying to parse a very irregular text file into columns.