message: Handle .set/.remove results from backend
diff: @@ -87,8 +87,9 @@ pub fn do_write<S: Storage, Q: Querier>(ctx: &Ctx, key_ptr: u32, value_ptr: u32)
  Err(_) => return ERROR_REGION_READ_UNKNOWN,
  };
  match with_storage_from_context::<S, Q, _, ()>(ctx, |store| {
  - store.set(&key, &value);
  - Ok(())
  + store
  + .set(&key, &value)
  + .or_else(|_| make_runtime_err("Error setting database value in backend"))
  }) {
  Ok(_) => SUCCESS,
  Err(Error::UninitializedContextData { .. }) => ERROR_NO_CONTEXT_DATA,
  @@ -103,8 +104,9 @@ pub fn do_remove<S: Storage, Q: Querier>(ctx: &Ctx, key_ptr: u32) -> i32 {
  Err(_) => return ERROR_REGION_READ_UNKNOWN,
  };
  match with_storage_from_context::<S, Q, _, ()>(ctx, |store| {
  - store.remove(&key);
  - Ok(())
  + store
  + .remove(&key)
  + .or_else(|_| make_runtime_err("Error removing database key from backend"))
  }) {
  Ok(_) => SUCCESS,
  Err(Error::UninitializedContextData { .. }) => ERROR_NO_CONTEXT_DATA,
  