message: Fix implicit conversion warning (string literal -> bool).
diff: @@ -420,7 +420,7 @@ void SlabAlloc::do_free(ref_type ref, const char* addr) noexcept
  // Check for double free
  for (auto& c : free_space) {
  if ((ref >= c.ref && ref < (c.ref + c.size)) || (ref < c.ref && ref_end > c.ref)) {
  - REALM_ASSERT(!"Double Free");
  + REALM_ASSERT(false && "Double Free");
  }
  }
  #endif
  