message: Make handler type explicit to use the same in std and vm
diff: @@ -3,7 +3,7 @@ use std::collections::HashMap;
  use crate::coins::Coin;
  use crate::encoding::Binary;
  -use crate::errors::{generic_err, invalid_utf8, StdResult, SystemError};
  +use crate::errors::{generic_err, invalid_utf8, StdResult, SystemError, SystemResult};
  use crate::query::{
  AllBalanceResponse, AllDelegationsResponse, BalanceResponse, BankQuery, BondedDenomResponse,
  DelegationResponse, FullDelegation, QueryRequest, StakingQuery, Validator, ValidatorsResponse,
  @@ -171,7 +171,10 @@ impl<C: Clone + DeserializeOwned> MockQuerier<C> {
  self.staking = StakingQuerier::new(denom, validators, delegations);
  }
  - pub fn with_custom_handler(mut self, handler: Box<dyn Fn(C) -> QuerierResult>) -> Self {
  + pub fn with_custom_handler(
  + mut self,
  + handler: Box<dyn Fn(C) -> SystemResult<StdResult<Binary>>>,
  + ) -> Self {
  self.handle_custom = handler;
  self
  }
  