#Error handling query (1 Viewer)

Hi - First post for me here.
I'm trying to split out the first name from a GivenNames field which contains first and middle names. Some values in the GivenNames field have just a first name. I've tried the below formula, but still get some #Error responses where only a first name exists in the field. It's probably just a bracket in the wrong place, but some help would be great.

My formula:
Given Name: IIf(IsError(Left([GivenNames],InStr([GivenNames]," ")-1)),[GivenNames],Left([GivenNames],InStr([GivenNames]," ")-1))

try IIf(InStr([GivenNames]," ")=0,[GivenNames],Left([GivenNames],InStr([GivenNames]," ")-1))

... yep, cheers - that seemed to work.