fix: race condition on repaint

[geodimm]

I noticed that there's a race condition when resizing windows. It's happening because the main tea Program loop calls repaint()

bubbletea/tea.go

Line 506 in b566614

p.renderer.repaint()

and the renderer is also setting the value of its lastRender:

bubbletea/standard_renderer.go

Line 210 in b566614

r.lastRender = r.buf.String()

This can be reproduced with the textinput example. Simply run it and resize your terminal window.

Output:

$ go run -race test.go
What’s your favorite Pokémon?

> Pikachu

(esc to quit)
==================
WARNING: DATA RACE
Write at 0x00c00014c198 by main goroutine:
  github.com/charmbracelet/bubbletea.(*standardRenderer).repaint()
      my-project/vendor/github.com/charmbracelet/bubbletea/standard_renderer.go:233 +0x39
  github.com/charmbracelet/bubbletea.(*Program).StartReturningModel()
      my-project/vendor/github.com/charmbracelet/bubbletea/tea.go:506 +0x1b17
  github.com/charmbracelet/bubbletea.(*Program).Start()
      my-project/vendor/github.com/charmbracelet/bubbletea/tea.go:547 +0xa4
  main.main()
      my-project/main.go:14 +0xa5

Previous write at 0x00c00014c198 by goroutine 9:
  github.com/charmbracelet/bubbletea.(*standardRenderer).flush()
      my-project/vendor/github.com/charmbracelet/bubbletea/standard_renderer.go:210 +0xd04
  github.com/charmbracelet/bubbletea.(*standardRenderer).listen()
      my-project/vendor/github.com/charmbracelet/bubbletea/standard_renderer.go:101 +0x124
  github.com/charmbracelet/bubbletea.(*standardRenderer).start.func1()
      my-project/vendor/github.com/charmbracelet/bubbletea/standard_renderer.go:69 +0x39

Goroutine 9 (running) created at:
  github.com/charmbracelet/bubbletea.(*standardRenderer).start()
      my-project/vendor/github.com/charmbracelet/bubbletea/standard_renderer.go:69 +0x156
  github.com/charmbracelet/bubbletea.(*Program).StartReturningModel()
      my-project/vendor/github.com/charmbracelet/bubbletea/tea.go:413 +0xda1
What’s your favorite Pokémon?

> Pikachu

(esc to quit)

[muesli]

Great find. We should probably enable the race detector in the CI.