Merge pull request #4365 from nextcloud/backport/4359/stable3.4

				const size = file.size

				let type = file.type

				// Handle cases where we are running inside a browser on Windows

				//

				// Developers are advised not to rely on the type as a sole validation scheme.

				// https://developer.mozilla.org/en-US/docs/Web/API/File/type

				// "Uncommon" file-extensions will result in an empty type

				// and apparently Microsoft considers calendar files to be "uncommon"

				if (type === '') {

				if (!this.supportedFileTypes.includes(type)) {

					// Try to guess file type based on its extension.

					// If it's an xml file, our best guess is xCal: https://tools.ietf.org/html/rfc6321

					// If it's a json file, our best guess is jCal: https://tools.ietf.org/html/rfc7265

					// In every other case, our best guess is just plain old iCalendar: https://tools.ietf.org/html/rfc5545

					}

				}

				// Make sure the user didn't select

				// files of a different file-type

				if (!this.supportedFileTypes.includes(type)) {

					showError(this.$t('calendar', '{filename} is an unsupported file-type', {

						filename: name,

					}))

					continue

				}

				// Use custom-options for parser.

				// The last one in particular will prevent thousands

				// of invitation emails to be sent out on import