From b5d4289f1be4cb037293bce70524457d18db964e Mon Sep 17 00:00:00 2001
From: Paul DeMarco <paulmdemarco@gmail.com>
Date: Wed, 8 Apr 2020 17:49:40 -0400
Subject: [PATCH] Add state check before discoverServices is called. (#537)

---
 lib/src/bluetooth_device.dart | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/lib/src/bluetooth_device.dart b/lib/src/bluetooth_device.dart
index 3c0bca46..e6be12e7 100644
--- a/lib/src/bluetooth_device.dart
+++ b/lib/src/bluetooth_device.dart
@@ -53,6 +53,11 @@ class BluetoothDevice {
 
   /// Discovers services offered by the remote device as well as their characteristics and descriptors
   Future<List<BluetoothService>> discoverServices() async {
+    final s = await state.first;
+    if (s != BluetoothDeviceState.connected) {
+      return Future.error(new Exception(
+          'Cannot discoverServices while device is not connected. State == $s'));
+    }
     var response = FlutterBlue.instance._methodStream
         .where((m) => m.method == "DiscoverServicesResult")
         .map((m) => m.arguments)