AppleScript in Editor vs. Launch Agent

Hello,

I have an AppleScript (script below) that runs fine in the AppleScript Editor. When I run the script using a Launch Agent (XML below) the script fails with no errors. I added some logging ("do shell script "logger -t sendername message"") to help with troubleshooting and a screenshot of that log activity is below.

The Red highlighted section is when the script runs as a result of the Plist. The Geen highlighted section is when the script runs in the AppleScript Editor. It appears to fail at the point where it enters the loop to do the deletions in the collection.

I can't for the life of me figure out why this is happening. The logged in user is the Administrator and I assume the Launch Agent (saved in ~/Library/LaunchAgents) is running as the logged-in user. But this would also be the case for the AppleScript Editor, correct?

AppleScript:

property kFileList : {}

set deletedFiles to 0
set source_folder to "Soft Proofs:SoftProofs"
set t to "SoftProofsCleanupScript"
set m to "Searching..."

do shell script "logger -t " & t & space & m

my createList(source_folder as alias)

set m to "Done searching, beginning delete..."

do shell script "logger -t " & t & space & m

with timeout of 600 seconds
    set m to "Beginning delete operations."
    do shell script "logger -t " & t & space & m
    
    repeat with theItem in kFileList
        set theFileName to the quoted form of (POSIX path of ((source_folder & ":" & theItem) as alias))
        
        try
            
            do shell script "rm -rf " & theFileName
            set deletedFiles to deletedFiles + 1
            
        on error errMsg
            do shell script "logger -t " & t & space & "Error: " & errMsg
            
        end try
        
    end repeat
    
    do shell script "logger -t " & t & space & "Deleted " & deletedFiles & " files."
end timeout

return kFileList

on createList(mSource_folder)
    set oldestAllowedDate to (current date) - 2 * days
    set item_list to ""
    
    tell application "System Events"
        set item_list to get the name of every disk item of mSource_folder
    end tell
    
    set item_count to (get count of items in item_list)
    
    repeat with i from 1 to item_count
        set the_properties to ""
        
        set the_item to item i of the item_list
        set the_item to ((mSource_folder & the_item) as string) as alias
        
        tell application "System Events"
            set file_info to get info for the_item
        end tell
        
        if visible of file_info is true then
            if modification date of file_info is less than oldestAllowedDate then
                set file_name to displayed name of file_info
                set end of kFileList to file_name
                if folder of file_info is true then
                    my createList(the_item)
                end if
            end if
        end if
        
    end repeat
end createList

.plist XML:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
    <key>Disabled</key>
    <false/>
    <key>Label</key>
    <string>com.thgraphics.CleanupSoftProofs</string>
    <key>ProgramArguments</key>
    <array>
        <string>osascript</string>
        <string>/Volumes/System/Users/admin/Documents/SoftProofsCleanupScript.scpt</string>
    </array>
    <key>RunAtLoad</key>
    <true/>
    <key>StartInterval</key>
    <integer>1800</integer>
</dict>
</plist>