When input is null, plugin runs error

[utbuiquoc]

I've just started using neovim, I'm not sure why I'm getting this error.
Add input and it works, if not add input will run error.

Error executing luv callback:
...re/nvim/lazy/competitest.nvim/lua/competitest/runner.lua:214: bad argument #2 to 'write' (data must be string or table of strings, got nil)
stack traceback:
        [C]: in function 'write'
        ...re/nvim/lazy/competitest.nvim/lua/competitest/runner.lua:214: in function 'execute_testcase'
        ...re/nvim/lazy/competitest.nvim/lua/competitest/runner.lua:129: in function 'run_first_testcases'
        ...re/nvim/lazy/competitest.nvim/lua/competitest/runner.lua:139: in function 'callback'
        ...re/nvim/lazy/competitest.nvim/lua/competitest/runner.lua:202: in function <...re/nvim/lazy/competitest.nvim/lua/competitest/runner.lua:168>
Press ENTER or type command to continue
Error executing luv callback:
...re/nvim/lazy/competitest.nvim/lua/competitest/runner.lua:170: attempt to index field 'process' (a nil value)
stack traceback:
        ...re/nvim/lazy/competitest.nvim/lua/competitest/runner.lua:170: in function <...re/nvim/lazy/competitest.nvim/lua/competitest/runner.lua:168>
Press ENTER or type command to continue

[xeluxee]

As README.md states,

Input is necessary for a testcase to be considered, while an output hasn't to be provided necessarily

As a workaround if your program doesn't use stdin you can still write something in testcase input, like a space.
I can fix this, but why would you need an empty input in a competitive programming task?

[utbuiquoc]

Sorry to bother, I just find it a bit annoying when it shows the error.