Adding callback for closing the tracer

Author: Ashish Aggarwal

src/configuration.ts

@@ -33,7 +33,7 @@ export default class Configuration {
                 case 'in_memory':
                     return new InMemoryDispatcher();
                 default:
-                    throw new Error(`reporter of type ${dispatcher} is not unknown`);
+                    throw new Error(`dispatcher of type ${dispatcher} is not unknown`);
             }
         }
         return new NoopDispatcher();

src/tracer.ts

@@ -112,11 +112,14 @@ export default class Tracer {
         return this._dispatcher;
     }
 
-    close(): void {
+    close(callback: () => void): void {
         this._dispatcher.close(() => {
             if (this._logger) {
                 this._logger.info('Tracer has been closed now.');
             }
+            if (callback) {
+                callback();
+            }
         });
     }