Checks to see if its first argument is an error. If the value isn't an error it is returned as-is, otherwise a secondary value is returned.
IfError([Primary Value], [Error Replacement Value])
Primary Value is the value to check for an error.
Error Replacement Value is the value to use if the primary value is an error.
|IfError(DWVariableLength,2475)||Will return 2475 when the value coming from the variable Length is an error.|