UnhandledRejection: t.file is undefined

Metrics for Event Action: UnhandledRejection - {
	"message":"t.file is undefined",
	"name":"TypeError",
	"fileName":"https://esign.tugraz.at/dbp-qualified-signature-pdf-upload.js",
	"lineNumber":393,
	"columnNumber":1,
	"stack":"getErrorFilesHtml/<@https://esign.tugraz.at/dbp-qualified-signature-pdf-upload.js:393:1
getErrorFilesHtml@https://esign.tugraz.at/dbp-qualified-signature-pdf-upload.js:375:218
render@https://esign.tugraz.at/dbp-qualified-signature-pdf-upload.js:592:2451
update@https://esign.tugraz.at/shared/adapter-lit-element.985f922b.es.js:180:1376
update@https://esign.tugraz.at/shared/activity.cde963e5.es.js:2365:691
update@https://esign.tugraz.at/dbp-qualified-signature-pdf-upload.js:31:9061
performUpdate@https://esign.tugraz.at/shared/adapter-lit-element.985f922b.es.js:155:6673
_enqueueUpdate@https://esign.tugraz.at/shared/adapter-lit-element.985f922b.es.js:155:6325
"}

from matomo, firefox 88