void tud_hid_report_complete_cb(uint8_t instance, uint8_t const* report, uint8_t len)

[m0uat]

The function prototype did not match the function in keyboard.c, the len var changed to uint16_t from uint8_t:

void tud_hid_report_complete_cb(uint8_t instance, uint8_t const* report, uint16_t len)

[ncw]

Do you want to send a pull request @m0uat ? Thanks