System Events not running

Hello!
I made an AppleScript that uses variables that changes by 1 every second, in the original version, it just tells System Events to type, but I kept getting errors so I changed it to tell System Events to activate and type something. The code works, but on the lines of code that tell System Events to activate, at a random time I get an error saying System Events is not running on the line of code telling it to activate. I am very confused. I will attach the error message as well as the code. The code is from a friend, I am just posting it for him.

Script Error
Application isn't running

Code Block applescript
tell application "System Events" to activate
tell application "System Events" to activate
set beg to 0
set mc to 0
set hour to 0
set search to 0
set pet to 0
set hl to 0
set ud to 0
set pm to 0
set ud to 0
set searchresult to 0
set listhl to {"h", "l"}
set listpm to {"f", "k"}
set listsearch to {"north pole", "advent calendar", "mistletoe", "christmas tree", "christmas card"}
delay 1
set ud to some item of listhl
set pm to some item of listpm
set searchresult to some item of listsearch
set reset to 0
delay 9
tell application "System Events"
	keystroke "pls daily"
	key code 36
	delay 0.5
	keystroke "pls beg"
	key code 36
	delay 0.5
	keystroke "pls hunt"
	key code 36
	delay 0.5
	keystroke "pls fish"
	key code 36
	delay 1
	keystroke "pls hl"
	key code 36
	delay 2
	keystroke ud
	key code 36
	delay 2
	keystroke "pls pm"
	key code 36
	delay 2
	keystroke pm
	key code 36
	delay 2
	keystroke "pls search"
	key code 36
	delay 1
	keystroke searchresult
	key code 36
	set ud to 0
	set pm to 0
	set searchresult to 0
	delay 1
	set ud to some item of listhl
	set pm to some item of listpm
	set searchresult to some item of listsearch
	
	
	repeat
		set beg to beg + 1
		set mc to mc + 1
		set hour to hour + 1
		set search to search + 1
		set pet to pet + 1
		set hl to hl + 1
		delay 1
		
		
		
		if hl = 22 then
			tell application "System Events" to activate
			tell application "Google Chrome" to activate
			tell application "System Events"
				set hl to 0
				keystroke "pls hl"
				key code 36
				delay 1
				keystroke ud
				key code 36
				set ud to 0
				delay 1
				set ud to some item of listhl
			end tell
		end if
		
		
		
		if beg = 47 then
			tell application "System Events" to activate
			tell application "Google Chrome" to activate
			tell application "System Events"
				keystroke "pls beg"
				key code 36
				set beg to 0
			end tell
		end if
		
		if mc = 62 then
			tell application "System Events" to activate
			tell application "Google Chrome" to activate
			tell application "System Events"
				set mc to 0
				keystroke "pls hunt"
				key code 36
				keystroke "pls fish"
				key code 36
				delay 6
				keystroke "pls pm"
				key code 36
				delay 2
				keystroke pm
				key code 36
				set pm to 0
				delay 1
				set pm to some item of listpm
			end tell
		end if
		
		if hour = 3600 then
			tell application "System Events" to activate
			tell application "Google Chrome" to activate
			tell application "System Events"
				keystroke "pls hourly"
				key code 36
				delay 1
				keystroke "pls daily"
				key code 36
				set hour to 0
			end tell
		end if
		
		if search = 37 then
			set search to 0
			tell application "System Events" to activate
			tell application "Google Chrome" to activate
			tell application "System Events"
				keystroke "pls search"
				key code 36
				delay 1
				keystroke searchresult
				key code 36
				set searchresult to 0
				delay 1
				set searchresult to some item of listsearch
			end tell
		end if
		
		if pet = 1800 then
			set pet to 0
			tell application "System Events"
				keystroke "pls pet pat"
				key code 36
				keystroke "pls pet feed"
				key code 36
				if reset = 50 then
					set reset to 0
					tell application "System Events" to activate
				end if
			end tell
		end if
	end repeat
end tell
end
end
end
end
end
end