Update a Taildrop error message (#4818)

ipn/ipnlocal: update error message on Taildrop send while not connected

Signed-off-by: Praneet <1466314+praneetloke@users.noreply.github.com>

ipn/ipnlocal/local.go

@@ -3108,7 +3108,7 @@ func (b *LocalBackend) FileTargets() ([]*apitype.FileTarget, error) {
 	defer b.mu.Unlock()
 	nm := b.netMap
 	if b.state != ipn.Running || nm == nil {
-		return nil, errors.New("not connected")
+		return nil, errors.New("not connected to the tailnet")
 	}
 	if !b.capFileSharing {
 		return nil, errors.New("file sharing not enabled by Tailscale admin")

ipn/ipnlocal/local_test.go

@@ -511,13 +511,13 @@ func TestLazyMachineKeyGeneration(t *testing.T) {
 func TestFileTargets(t *testing.T) {
 	b := new(LocalBackend)
 	_, err := b.FileTargets()
-	if got, want := fmt.Sprint(err), "not connected"; got != want {
+	if got, want := fmt.Sprint(err), "not connected to the tailnet"; got != want {
 		t.Errorf("before connect: got %q; want %q", got, want)
 	}
 
 	b.netMap = new(netmap.NetworkMap)
 	_, err = b.FileTargets()
-	if got, want := fmt.Sprint(err), "not connected"; got != want {
+	if got, want := fmt.Sprint(err), "not connected to the tailnet"; got != want {
 		t.Errorf("non-running netmap: got %q; want %q", got, want)
 	}