fix(healthcheck): prevent race condition on the healthchecker (#3400)

Co-authored-by: Matt Van Horn <455140+mvanhorn@users.noreply.github.com>
Co-authored-by: Quentin McGaw <quentin.mcgaw@gmail.com>

Thanks also to @arturhoo for also trying to resolve this issue in #3410

internal/vpn/loop.go

@@ -45,6 +45,7 @@ type Loop struct {
 	start       <-chan struct{}
 	running     chan<- models.LoopStatus
 	userTrigger bool
+	healthDone  <-chan struct{}
 	// Internal constant values
 	backoffTime time.Duration
 }
@@ -70,6 +71,11 @@ func NewLoop(vpnSettings settings.VPN, ipv6SupportLevel netlink.IPv6SupportLevel
 	statusManager := loopstate.New(constants.Stopped, start, running, stop, stopped)
 	state := state.New(statusManager, vpnSettings)
 
+	// Initialize healthDone channel to a closed channel so that the first time
+	// we call <-l.healthDone it does not block
+	healthDone := make(chan struct{})
+	close(healthDone)
+
 	return &Loop{
 		statusManager:    statusManager,
 		state:            state,
@@ -98,6 +104,7 @@ func NewLoop(vpnSettings settings.VPN, ipv6SupportLevel netlink.IPv6SupportLevel
 		stop:             stop,
 		stopped:          stopped,
 		userTrigger:      true,
+		healthDone:       healthDone,
 		backoffTime:      defaultBackoffTime,
 	}
 }