ng-file-upload: Invalid file types are correctly not added to the model but turn the form invalid

So I have this snippet which actually works fine adding multiple files on multiple drags/selects, until I add an invalid file type. The invalid file type is not added to the model but will make the form invalid. The form becomes valid again when I add/append another valid file to the list. I tried put allowInvalid false, ngf-valid-only but none of them solve my problem. Always get the form.files.$error = {“pattern”:true} when adding an invalid file. How can I make these unsupported file types not turn the form invalid?

<div name="files" ngf-drop ngf-select ng-model="ui.files" class="drop-box"  
   ng-model-options="{allowInvalid: false}"
   ngf-drag-over-class="{accept:'dragover', reject: 'reject-dragover'}" 
   ngf-multiple="true" ngf-allow-dir="true"
   accept="{{ui.validFileTypes}}" ngf-keep="true" ngf-valid-only="true"
   ngf-change="filesChanged()"
   ngf-pattern="ui.validFileTypes" required>
</div>