fix bad null ref, add test for the future

Author: TerribleDev

src/StatsN.UnitTests/StastdTests.cs

@@ -49,6 +49,17 @@ public void EscapeDots()
             Assert.Equal("awesome", options.Prefix);
         }
         [Fact]
+        public void ConstructWithoutProvider()
+        {
+            //check to make sure the constructor doesn't blow
+            var t = new Statsd(new StatsdOptions()
+            {
+                OnExceptionGenerated = (exception) => { throw exception; }
+            });
+            t.CountAsync("awesome").GetAwaiter().GetResult();
+            t.Dispose();
+        }
+        [Fact]
         public void CorrectMetricTypesPassed()
         {
             var statsd = Statsd.New<NullChannel>(a => { a.HostOrIp = "localhost"; a.OnExceptionGenerated = (b) => { throw b; }; });

src/StatsN/Statsd.cs

@@ -60,7 +60,7 @@ public Statsd(StatsdOptions options, BaseCommunicationProvider provider = null)
             }
             if(provider == null)
             {
-                _provider = new Udp();
+                provider = new Udp();
             }
             if (string.IsNullOrEmpty(options.HostOrIp))
             {