Whilst in a petrified condition (i.e. 'turned to stone') how does such a creature heal? In 5e D&D this condition on creatures presents as 'target is incapacitated + stone-flavoured' (PhB 'Conditions' / p.291).
How can damage to a petrified creature be healed?
Possible solutions mentioned by other DMs:
This creature qualifies as 'incapacitated', thus it can heal as any other creature. Fed potions by allies (?), First Aid bandages or even a good night's rest.
Petrified beings are obviously stone statues. A Mending spell (PhB, p. 259) will re-affix any damage to any construct (such as: broken finger, arm or even neck), so long as this is less than a square foot of surface area. Heals of any sort would not work because this thing cannot bleed, respirate or otherwise benefit from life-enhancing supports (magical or otherwise). Example: a badly injured / dying warrior is medically scratched by a Cockatrice (MM p.42) claw. Then the medic uses Stone Shape (PhB p.278) to fix all wounds and re-attach all parts - possibly even adding some muscles before the magic ends in 24 hours.
This is a form of suspended animation and not subject to healing tomfoolery. If brought to zero hit points the stone creature suffers organ shock and bleeds out as pre-established by RAW.
This is a role-playing fantasy game - work with the narrative. Logically, wounds before becoming a statue are healed with magical aid. Damage done after petrification is repaired magically as pottery or other stonewares. Non-magical means (Band-Aid®, Crazy Glue® or otherwise) simply do NOT work.
Are there any official rules (in books, including VGM or XGtE or Crawford's tweets) clarifying this matter?