UpdateFunction throwing nil and I have no idea why

--[[
		CoreAPI is designed to provide some of the regularly needed
		features of general types of programs in one place.

		It is a mish-mash of functions where I wasn't sure where to place
		elsewhere.
		]]

version = "0.0.1"

--==Startup Functions==--

--Test This
function setStartup(...)
  --Takes any number of arguments and creates
  --a startup script to execute the program (argument 1)
  --with any following parameters (arguments afterwards)

  local args = {...}

  --Making sure I don't break a previous startup
  if fs.exists("startup") then
		fs.move("startup", "oldStartup")
  end

  --Saving the params file
  if not fs.exists("tempFiles/") then
		fs.makeDir("tempFiles")
  end

  local tempStartupParams = fs.open("tempFiles/tempStartupParams", "w")
  tempStartupParams.write(textutils.serialize(args))
  tempStartupParams.close()

  --Generating the startup file
  local startupFile = fs.open("startup", "w")
  startupFile.writeLine("--If you can read this, remove it")
  startupFile.writeLine("local params = fs.open(\"tempFiles/tempStartupParams\", \"r\")")
  startupFile.writeLine("local args = textutils.unserialize(params.readAll())")
  startupFile.writeLine("params.close()")
  startupFile.writeLine("shell.run(unpack(args))")
  startupFile.close()
end

function removeStartup()
		--Removes the startup you created and sets old one
		--(if it exists), back to normal place

		--Removes set startup and puts new one back
		if fs.exists("oldStartup") then
				if fs.exists("startup") then
						fs.delete("startup")
				end
				fs.move("oldStartup", "startup")
		end

		--Gets rid of the tempFiles Folder
		if fs.exists("tempFiles") then
				fs.delete("tempFiles")
		end
end

--==Update Functions==--

function checkUpdate(pastebinExtension, programPath)
		--Downloads the latest version of the program and compares size.
		--If size is different, it deletes the old and replaces with the new
		--Returns true if there was an update.

		print("Checking for updates...")
		shell.run("pastebin", "get", pastebinExtension, programPath.."temp")
		if fs.exists(programPath) then
				if fs.getSize(programPath) == fs.getSize(programPath.."temp") then
						fs.delete(programPath.."temp")
						print("You are up to date.")
						return false
				else
						print("Updates found. Applying...")
						fs.delete(programPath)
						fs.move(programPath.."temp", programPath)
						print("Done!")
						return true
				end
		else
				print("Updates found. Applying...")
				fs.move(programPath.."temp", programPath)
				print("Done!")
				return true
		end
end

function updateApis()
		--Updates/Downloads newest renditions of
		--my APIs (including this one)
		checkUpdate("kvLnweEf", "api/core")
		checkUpdate("9QFxP4Ff", "api/move")
		checkUpdate("E4cPHATD", "api/network")
end