Hi,
I’ve just noticed that the requiresES6 option is marked as removed since version 1.42. However, it seems that it is not the case. I tried removing it from a gadget’s definition on frwikt (which is on version 1.44 according to its fr:Special:Version page) and it broke the gadget. Moreover, the fr:Special:Gadgets page shows a specific text when the option is specified, hinting that the option might still in fact be supported.
Is this an error on the extension’s page or am I missing something?