fix: initialize Program fields in init method

tea.go

@@ -275,12 +275,7 @@ func Interrupt() Msg {
 
 // NewProgram creates a new Program.
 func NewProgram[T any](model Model[T], opts ...ProgramOption[T]) *Program[T] {
-	p := &Program[T]{
-		msgs:         make(chan Msg),
-		rendererDone: make(chan struct{}),
-		modes:        make(map[ansi.DECMode]bool),
-		exp:          experimentalOptions{},
-	}
+	p := &Program[T]{}
 
 	p.Init = model.Init
 	p.Update = func(t T, msg Msg) (T, Cmd) {
@@ -297,6 +292,15 @@ func NewProgram[T any](model Model[T], opts ...ProgramOption[T]) *Program[T] {
 		opt(p)
 	}
 
+	return p
+}
+
+func (p *Program[T]) init() {
+	p.msgs = make(chan Msg)
+	p.rendererDone = make(chan struct{})
+	p.modes = make(map[ansi.DECMode]bool)
+	p.exp = experimentalOptions{}
+
 	// A context can be provided with a ProgramOption, but if none was provided
 	// we'll use the default background context.
 	if p.ctx == nil {
@@ -344,8 +348,6 @@ func NewProgram[T any](model Model[T], opts ...ProgramOption[T]) *Program[T] {
 	if exp := p.getenv("TEA_EXPERIMENTAL"); exp != "" {
 		p.exp = strings.Split(exp, ",")
 	}
-
-	return p
 }
 
 func (p *Program[T]) handleSignals() chan struct{} {
@@ -686,6 +688,8 @@ func (p *Program[T]) Run() error {
 }
 
 func (p *Program[T]) Start() error {
+	p.init()
+
 	p.handlers = channelHandlers{}
 	cmds := make(chan Cmd)
 	p.errs = make(chan error)