message: Adding input validation back
diff: @@ -53,7 +53,7 @@ export class AppInsightsCore implements IAppInsightsCore {
  this.logger = new DiagnosticLogger(config);
  // Initial validation
  - this._extensions.forEach((extension: ITelemetryPlugin) => {
  + extensions.forEach((extension: ITelemetryPlugin) => {
  if (CoreUtils.isNullOrUndefined(extension.initialize)) {
  throw Error(validationError);
  }
  