minor: fix fileList default

Props of type array need a factory function for their defaults.

Otherwise when reusing the component
all might end up with a shared default array.

Signed-off-by: Azul <azul@riseup.net>

Author: azul

js/viewer-main.js

@@ -55,7 +55,7 @@ export default {
 		// list of all the visible files
 		fileList: {
 			type: Array,
-			default: [],
+			default: () => [],
 		},
 		// file mime (aliased if specified in the model)
 		mime: {