message: Simplify call_migrate
diff: @@ -3,7 +3,7 @@ use std::fmt;
  use cosmwasm_std::{Env, HandleResult, InitResult, MigrateResult, QueryResult};
  -use crate::errors::{make_generic_err, make_resolve_err, VmResult};
  +use crate::errors::{make_generic_err, VmResult};
  use crate::instance::{Func, Instance};
  use crate::serde::{from_slice, to_vec};
  use crate::traits::{Api, Querier, Storage};
  @@ -108,13 +108,8 @@ pub fn call_migrate_raw<S: Storage + 'static, A: Api + 'static, Q: Querier + 'st
  env: &[u8],
  msg: &[u8],
  ) -> VmResult<Vec<u8>> {
  - // first check if migrate is not implemented and return a standard error message
  - if instance.func::<(u32, u32), u32>("migrate").is_err() {
  - Err(make_resolve_err("no migrate function exported by contract"))
  - } else {
  call_raw(instance, "migrate", &[env, msg], MAX_LENGTH_MIGRATE)
  }
  -}
  /// Calls Wasm export "query" and returns raw data from the contract.
  /// The result is length limited to prevent abuse but otherwise unchecked.
  