fixed some little UI bugs

- We could open the CDashDisplay specific layout before it existed -
Crash!
- We could open the stream UI before there was a provider- Crash!

services/devices.go

@@ -71,6 +71,14 @@ func (ds *DeviceService) GetDevice(name string) (devices.Device, error) {
 	return val, nil
 }
 
+func (ds *DeviceService) DeviceExists(name string) bool {
+	if _, ok := ds.Devices[name]; !ok {
+		return false
+	}
+
+	return true
+}
+
 func (ds *DeviceService) StartStream() {
 	// NOTE: i'm using this pattern a whole lot. Maybe I can create a struct to handle this
 	var ctx context.Context

services/telemetry.go

@@ -230,3 +230,11 @@ func (t *TelemetryService) StopStream() {
 
 	t.activeProvider.StopStream()
 }
+
+func (t *TelemetryService) HasActiveProvider() bool {
+	if t.activeProvider == nil {
+		return false
+	}
+
+	return true
+}