[BUG] Diagnostic failure

[sidlatau]

NeoVim Version
NVIM v0.11.0-dev-6292+g58406ab9f0-Homebrew
Build type: Release
LuaJIT 2.1.1727870382
Run "nvim -V1 -v" for more info

Describe the bug
Sometimes diagnostic fails:

neotest-dart: /Users/ts/.local/share/nvim/lazy/nvim-nio/lua/nio/init.lua:119: The coroutine failed with this message:                                
/Users/ts/.local/share/nvim/lazy/nvim-nio/lua/nio/tasks.lua:100: Async task failed without callback: The coroutine failed with this message:         
...ub/personal/neotest/lua/neotest/consumers/diagnostic.lua:88: attempt to index a nil value                                                         
stack traceback:                                                                                                                                     
        ...ub/personal/neotest/lua/neotest/consumers/diagnostic.lua: in function 'create_diagnostics'                                                
        ...ub/personal/neotest/lua/neotest/consumers/diagnostic.lua:54: in function 'draw_buffer'                                                    
        ...ub/personal/neotest/lua/neotest/consumers/diagnostic.lua:177: in function 'draw_buffer'                                                   
        ...ub/personal/neotest/lua/neotest/consumers/diagnostic.lua:239: in function 'listener'    

Expected behavior
Setting diagnostic should not crash tests.