fix: avoid Exec restore panic with WithInput(nil)

[lawrence3699]

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Summary

Fix the WithInput(nil) + ExecProcess panic reported in the #761 discussion.

Problem

#761 recommends tea.WithInput(nil) as the workaround when there is no TTY available. That works until a program executes tea.ExecProcess(...) and returns to Bubble Tea.

At that point RestoreTerminal() always called initInputReader(false), even when input had been explicitly disabled. That rebuilds the cancel reader with p.input == nil and panics in cancelreader.

Minimal repro:

func (m model) Init() tea.Cmd {
    return tea.ExecProcess(exec.Command("true"), func(err error) tea.Msg {
        return finishedMsg{err}
    })
}

func main() {
    _, err := tea.NewProgram(model{}, tea.WithInput(nil)).Run()
    if err != nil {
        panic(err)
    }
}

Fix

Make RestoreTerminal() match the initial startup path in Run() and only reinitialize the input reader when p.input != nil.

Added TestTeaExecWithNilInput to cover the regression.

Validation

• go test -run 'TestTeaExec|TestTeaExecWithNilInput' .
• go test ./...

[Copilot]

Pull request overview

Fixes a panic when running ExecProcess in a program configured with WithInput(nil) by ensuring terminal restoration does not attempt to reinitialize the input reader when input is explicitly disabled.

Changes:

• Update Program.RestoreTerminal() to only call initInputReader(false) when p.input != nil.
• Add a regression test covering ExecProcess with WithInput(nil) to prevent reintroducing the panic.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
tea.go	Prevents RestoreTerminal() from reinitializing the cancel reader when input is disabled (p.input == nil).
exec_test.go	Adds a regression test that runs ExecProcess under WithInput(nil) to ensure no panic and no error.

---

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[Copilot]

testExecNoInputModel embeds testExecModel, but it relies on the promoted Update method whose receiver is *testExecModel. That Update returns m (a *testExecModel), so after the first update the program’s model type changes from *testExecNoInputModel to *testExecModel. This is a bit brittle/confusing for a regression test; consider giving testExecNoInputModel its own Update/View (or avoid embedding) so it consistently returns the same concrete model type.

Suggested change

	func (m *testExecNoInputModel) Update(msg Msg) (Model, Cmd) {
	switch msg := msg.(type) {
	case execFinishedMsg:
	if msg.err != nil {
	m.err = msg.err
	}
	return m, Quit
	}
	return m, nil
	}
	func (m *testExecNoInputModel) View() View {
	return m.testExecModel.View()
	}

[codecov]

Codecov Report

❌ Patch coverage is 33.33333% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 55.64%. Comparing base (fdcd0cf) to head (8e05899).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
tea.go	33.33%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1680      +/-   ##
==========================================
+ Coverage   55.38%   55.64%   +0.26%     
==========================================
  Files          25       25              
  Lines        1309     1310       +1     
==========================================
+ Hits          725      729       +4     
+ Misses        493      491       -2     
+ Partials       91       90       -1     

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[aymanbagabas]

@lawrence3699 Thank you so much!