fix: wait for read-loop to finish before spawning child process

tea.go

@@ -292,13 +292,7 @@ func (p *Program) StartReturningModel() (Model, error) {
 
 		waitForGoroutines = func(withReadLoop bool) {
 			if withReadLoop {
-				select {
+				p.waitForReadLoop()
-				case <-p.readLoopDone:
-				case <-time.After(500 * time.Millisecond):
-					// The read loop hangs, which means the input
-					// cancelReader's cancel function has returned true even
-					// though it was not able to cancel the read.
-				}
 			}
 			<-cmdLoopDone
 			<-resizeLoopDone
@@ -712,6 +706,8 @@ func (p *Program) DisableMouseAllMotion() {
 func (p *Program) ReleaseTerminal() error {
 	p.ignoreSignals = true
 	p.cancelInput()
+	p.waitForReadLoop()
+
 	p.altScreenWasActive = p.altScreenActive
 	if p.altScreenActive {
 		p.ExitAltScreen()

tty.go

@@ -3,6 +3,7 @@ package tea
 import (
 	"errors"
 	"io"
+	"time"
 
 	"github.com/muesli/cancelreader"
 )
@@ -48,7 +49,12 @@ func (p *Program) initCancelReader() error {
 	}
 
 	p.readLoopDone = make(chan struct{})
-	go func() {
+	go p.eventLoop()
+
+	return nil
+}
+
+func (p *Program) eventLoop() {
 	defer close(p.readLoopDone)
 
 	for {
@@ -69,12 +75,20 @@ func (p *Program) initCancelReader() error {
 			p.msgs <- msg
 		}
 	}
-	}()
-
-	return nil
 }
 
 // cancelInput cancels the input reader.
 func (p *Program) cancelInput() {
 	p.cancelReader.Cancel()
 }
+
+// waitForReadLoop waits for the cancelReader to finish its read loop.
+func (p *Program) waitForReadLoop() {
+	select {
+	case <-p.readLoopDone:
+	case <-time.After(500 * time.Millisecond):
+		// The read loop hangs, which means the input
+		// cancelReader's cancel function has returned true even
+		// though it was not able to cancel the read.
+	}
+}