Ensure that file is not attached if we've filtered it

js/views/file_input_view.js

@@ -184,6 +184,8 @@
       }
       const { name } = file;
       if (window.Signal.Util.isFileDangerous(name)) {
+        this.deleteFiles();
+
         const toast = new Whisper.DangerousFileTypeToast();
         toast.$el.insertAfter(this.$el);
         toast.render();