nodemcu-firmware: The LGC usage count is incorrectly calculated if luaM_free() is used to free arrays in our modules

Expected behavior

Read line, no permanent memory consumption.

Actual behavior

Readline works, but causes permanent memory consumption.

Console output directly after startup:

=collectgarbage(“count”) 4

Function is run via console:

increment_job_counter()

Memory usage increases:

=collectgarbage(“count”) 5

increment_job_counter() =collectgarbage(“count”) 6

increment_job_counter() =collectgarbage(“count”) 7

collectgarbage() =collectgarbage(“count”) 7

This example can be continued until memory overflow error occurrs.

Test code

This is my minimalistic init.lua

function increment_job_counter()
	if file.exists("job.counter") == true then
		local handle = file.open("job.counter", "r")
		local val = tonumber(file.readline()) + 1
		handle = file.open("job.counter", "w+")
		handle:writeline(tostring(val))
		handle:close()
		handle = nil
		val = nil
	else
		local handle = file.open("job.counter", "w+")
		handle:writeline(tostring(1))
		handle:close()
		handle = nil
	end
end

NodeMCU version

branch: master (latest) commit: 67027c0d05f7e8d1b97104e05a3715f6ebc8d07f

Hardware

Wemos D1 mini pro