check for valid terminal

internal/terminal/terminal.go

@@ -2,12 +2,22 @@ package terminal
 
 import (
 	"fmt"
-	"golang.org/x/term"
 	"os"
+
+	"golang.org/x/term"
 )
 
+// Is this a valid interactive terminal?
+func check() {
+	if !term.IsTerminal(int(os.Stdin.Fd())) {
+		panic("An interactive terminal is required to use a text editor!")
+	}
+}
+
 // Put the terminal in raw mode
 func RawOn() *term.State {
+	check()
+
 	oldState, err := term.MakeRaw(int(os.Stdin.Fd()))
 	if err != nil {
 		panic(err)
@@ -29,4 +39,4 @@ func OutLn(format string, a ...interface{}) {
 	formatted := fmt.Sprintf(format, a...)
 
 	fmt.Printf("%s\r\n", formatted)
-}
+}