ngx-uploader: Everything working fine, but this error message: ... what does it mean?

error_handler.js:50 EXCEPTION: _this.files.filter is not a function ErrorHandler.handleError @ error_handler.js:50 next @ application_ref.js:346 schedulerFn @ async.js:91 SafeSubscriber.__tryOrUnsub @ Subscriber.js:223 SafeSubscriber.next @ Subscriber.js:172 Subscriber._next @ Subscriber.js:125 Subscriber.next @ Subscriber.js:89 Subject.next @ Subject.js:55 EventEmitter.emit @ async.js:77 NgZone.triggerError @ ng_zone.js:329 onHandleError @ ng_zone.js:290 ZoneDelegate.handleError @ zone.js:246 Zone.runTask @ zone.js:154 ZoneTask.invoke @ zone.js:345 error_handler.js:55 ORIGINAL STACKTRACE: ErrorHandler.handleError @ error_handler.js:55 next @ application_ref.js:346 schedulerFn @ async.js:91 SafeSubscriber.__tryOrUnsub @ Subscriber.js:223 SafeSubscriber.next @ Subscriber.js:172 Subscriber._next @ Subscriber.js:125 Subscriber.next @ Subscriber.js:89 Subject.next @ Subject.js:55 EventEmitter.emit @ async.js:77 NgZone.triggerError @ ng_zone.js:329 onHandleError @ ng_zone.js:290 ZoneDelegate.handleError @ zone.js:246 Zone.runTask @ zone.js:154 ZoneTask.invoke @ zone.js:345 error_handler.js:56 TypeError: _this.files.filter is not a function at ng-file-select.ts:41 at SafeSubscriber.schedulerFn [as _next] (async.js:103) at SafeSubscriber.__tryOrUnsub (Subscriber.js:223) at SafeSubscriber.next (Subscriber.js:172) at Subscriber._next (Subscriber.js:125) at Subscriber.next (Subscriber.js:89) at EventEmitter.Subject.next (Subject.js:55) at EventEmitter.emit (async.js:77) at XMLHttpRequest.xhr.onreadystatechange (ng2-uploader.ts:103) at XMLHttpRequest.wrapFn [as _onreadystatechange] (zone.js:889) at ZoneDelegate.invokeTask (zone.js:275) at Object.onInvokeTask (ng_zone.js:260) at ZoneDelegate.invokeTask (zone.js:274) at Zone.runTask (zone.js:151) at XMLHttpRequest.ZoneTask.invoke (zone.js:345) ErrorHandler.handleError @ error_handler.js:56 next @ application_ref.js:346 schedulerFn @ async.js:91 SafeSubscriber.__tryOrUnsub @ Subscriber.js:223 SafeSubscriber.next @ Subscriber.js:172 Subscriber._next @ Subscriber.js:125 Subscriber.next @ Subscriber.js:89 Subject.next @ Subject.js:55 EventEmitter.emit @ async.js:77 NgZone.triggerError @ ng_zone.js:329 onHandleError @ ng_zone.js:290 ZoneDelegate.handleError @ zone.js:246 Zone.runTask @ zone.js:154 ZoneTask.invoke @ zone.js:345 ng-file-select.ts:41 Uncaught TypeError: _this.files.filter is not a function at ng-file-select.ts:41 at SafeSubscriber.schedulerFn [as _next] (async.js:103) at SafeSubscriber.__tryOrUnsub (Subscriber.js:223) at SafeSubscriber.next (Subscriber.js:172) at Subscriber._next (Subscriber.js:125) at Subscriber.next (Subscriber.js:89) at EventEmitter.Subject.next (Subject.js:55) at EventEmitter.emit (async.js:77) at XMLHttpRequest.xhr.onreadystatechange (ng2-uploader.ts:103) at XMLHttpRequest.wrapFn [as _onreadystatechange] (zone.js:889) at ZoneDelegate.invokeTask (zone.js:275) at Object.onInvokeTask (ng_zone.js:260) at ZoneDelegate.invokeTask (zone.js:274) at Zone.runTask (zone.js:151) at XMLHttpRequest.ZoneTask.invoke (zone.js:345)