Fix duplicate key error when exceptions occur (#323)

Author: Charles-Gagnon

src/TriggerBinding/SqlTriggerListener.cs

@@ -35,7 +35,7 @@ internal sealed class SqlTriggerListener<T> : IListener
         private readonly ITriggeredFunctionExecutor _executor;
         private readonly ILogger _logger;
 
-        private readonly IDictionary<TelemetryPropertyName, string> _telemetryProps;
+        private readonly IDictionary<TelemetryPropertyName, string> _telemetryProps = new Dictionary<TelemetryPropertyName, string>();
 
         private SqlTableChangeMonitor<T> _changeMonitor;
         private int _listenerState;
@@ -62,11 +62,6 @@ public SqlTriggerListener(string connectionString, string tableName, string user
             this._executor = executor;
             this._logger = logger;
             this._listenerState = ListenerNotStarted;
-
-            this._telemetryProps = new Dictionary<TelemetryPropertyName, string>
-            {
-                [TelemetryPropertyName.UserFunctionId] = this._userFunctionId,
-            };
         }
 
         public void Cancel()
@@ -81,6 +76,7 @@ public void Dispose()
 
         public async Task StartAsync(CancellationToken cancellationToken)
         {
+            this.InitializeTelemetryProps();
             TelemetryInstance.TrackEvent(TelemetryEventName.StartListenerStart, this._telemetryProps);
 
             int previousState = Interlocked.CompareExchange(ref this._listenerState, ListenerStarting, ListenerNotStarted);
@@ -439,5 +435,14 @@ PRIMARY KEY ({primaryKeys})
                 return stopwatch.ElapsedMilliseconds;
             }
         }
+
+        /// <summary>
+        /// Clears the current telemetry property dictionary and initializes the default initial properties. 
+        /// </summary>
+        private void InitializeTelemetryProps()
+        {
+            this._telemetryProps.Clear();
+            this._telemetryProps[TelemetryPropertyName.UserFunctionId] = this._userFunctionId;
+        }
     }
 }