fix: Limit open with Collabora action to pdf files

Signed-off-by: Julius Knorr <jus@bitgrid.net>

[skip ci]

src/file-actions.js

@@ -21,7 +21,12 @@ const openPdf = new FileAction({
 			{ productName: richdocuments.productName })
 	},
 
-	enabled: () => {
+	enabled: (files) => {
+		if (files.length !== 1) {
+			return false
+		}
+
+		const isPdf = files[0].mime === 'application/pdf'
 		// Only enable the file action when files_pdfviewer is enabled
 		const optionalMimetypes = richdocuments.mimetypesNoDefaultOpen
 		return optionalMimetypes.includes('application/pdf')