Getting filename from a selection in Finder

Hi, my apologies as I'm a newbie pasting and editing scripts... and I can't work out why something I've pasted that works in isolation is now giving me errors. It must be simple but I can't see it... please help?

I'm trying to change the date of a series of photos to the date in the filename, which seems a pretty common ask but I've not found a whole script solution. My script below gets as far as identifying the first file of a selection of files I've selected in Finder (yay!)... but then breaks when I try and select the filename of that file, before I can start extracting the date from it (using a pasted script). What am I doing wrong?!\

I get:

Result:

error "Can’t get filename of \"<name of file\"." number -1728 from filename of "<name of file"

From the below, I've added a "log" above where it breaks:

set originalDelimiters to AppleScript's text item delimiters

tell application "Finder"

	activate

	log "Starting...."

	set image_selection to {}

	set theItems to selection

	repeat with itemRef in theItems

		set end of image_selection to name of itemRef

	end repeat

	log image_selection

	set n_changed to 0

	if (image_selection is {}) then

		error "Please select at least one image."

	else

		repeat with i from 1 to count of image_selection

			set flag to true

			set image to item i of image_selection

			log "Help! It breaks on the line below here getting filename.."

			set image_name to filename of image

			log image_name