fix: reusing buffers crashing (nvim 0.11+)

[GustavEikaas]

Description

First of all thank you for a great plugin! Truly amazing work🧑‍🍳

From time to time I have been slapped with this stack trace but never been able to reproduce it reliably. After working on aspire support in my own plugin I managed to reproduce and debug.

It looks like an nvim-dap bug but nvim-dap is correctly calling jobstart{term = true} https://github.com/mfussenegger/nvim-dap/blob/master/lua/dap/session.lua#L271

dapui/elements/console.lua caches one module-level console_buf and registers dap.defaults.fallback.terminal_win_cmd = get_buf. Every runInTerminal reuses that single buffer. causing it to sometimes reuse a buffer that is already hosting a terminal.

nvim-dap/lua/dap/session.lua:269: Lua: Vim:jobstart(...,{term=true}) requires unmodified buffer
stack traceback:
    [C]: in function 'termopen'
    ...dmin/.local/share/nvim/lazy/nvim-dap/lua/dap/session.lua:272: in function <...dmin/.local/share/nvim/lazy/nvim-dap/lua/dap/session.lua:269>
    [C]: in function 'nvim_buf_call'
    ...dmin/.local/share/nvim/lazy/nvim-dap/lua/dap/session.lua:269: in function 'handler'
    ...dmin/.local/share/nvim/lazy/nvim-dap/lua/dap/session.lua:1129: in function 'handle_body'
    ...dmin/.local/share/nvim/lazy/nvim-dap/lua/dap/session.lua:1516: in function ''
    vim/_core/editor.lua: in function <vim/_core/editor.lua:0>
stack traceback:
    [C]: in function 'nvim_buf_call'
    ...dmin/.local/share/nvim/lazy/nvim-dap/lua/dap/session.lua:269: in function 'handler'
    ...dmin/.local/share/nvim/lazy/nvim-dap/lua/dap/session.lua:1129: in function 'handle_body'
    ...dmin/.local/share/nvim/lazy/nvim-dap/lua/dap/session.lua:1516: in function ''
    vim/_core/editor.lua: in function <vim/_core/editor.lua:0>

Minimal repro

1. nvim 0.11+/0.12, nvim-dap + nvim-dap-ui with a console element in the layout, a config with console = "integratedTerminal".
2. Debug any program → works. Stop. Debug again → throws. (Or start two integratedTerminal sessions concurrently → the 2nd throws.)

[GustavEikaas]

I have not tested this on pre nvim 0.11 but IMO that shouldnt be necessary