QuickPulseTelemetryModule.Dispose should not throw if module is not initialized

CHANGELOG.md

@@ -1,6 +1,7 @@
 # Changelog
 
 ## Version 2.10.0-beta3
+- [Fix: QuickPulseTelemetryModule.Dispose should not throw if module was not initialized](https://github.com/Microsoft/ApplicationInsights-dotnet-server/pull/1170)
 - Added NetStandard2.0 Target for PerfCounter project.
 - Added support for PerfCounters for .Net Core Apps in Windows.
 - Updated Base SDK to 2.10.0-beta3

Src/PerformanceCollector/Perf.Shared.Tests/QuickPulse/QuickPulseTelemetryModuleTests.cs

@@ -48,6 +48,13 @@ public void QuickPulseTelemetryModuleIsInitializedBySdk()
             new QuickPulseTelemetryModule().Initialize(configuration);
         }
 
+        [TestMethod]
+        public void QuickPulseTelemetryModuleDisposeWithoutInitialize()
+        {
+            var qp = new QuickPulseTelemetryModule();
+            qp.Dispose();
+        }
+
         [TestMethod]
         [ExpectedException(typeof(ArgumentNullException))]
         public void QuickPulseTelemetryModuleDoesNotRegisterNullProcessor()

Src/PerformanceCollector/Perf.Shared/QuickPulseTelemetryModule.cs

@@ -697,7 +697,11 @@ private void Dispose(bool disposing)
             {
                 Interlocked.Exchange(ref this.stateThread, null)?.Stop(wait: true);
                 Interlocked.Exchange(ref this.collectionThread, null)?.Stop(wait: true);
-                this.serviceClient.Dispose();
+
+                if (this.serviceClient != null)
+                {
+                    this.serviceClient.Dispose();
+                }
             }
         }
     }