why capture both this and thisp ? doing `thisp->errFlag = true;` would cost nothing and save 4/8 bytes. Also doing [thisp = shared_from_this()] would save

why capture both this and thisp ? doing `thisp->errFlag = true;` would cost nothing and save 4/8 bytes. Also doing [thisp = shared_from_this()] would save a potentially expensive atomic increment & decrement which happens when copying the shared_ptr