message: Standardize wasmer_instance access code
diff: @@ -180,12 +180,13 @@ impl<A: Api, S: Storage, Q: Querier> Environment<A, S, Q> {
  })
  }
  +
  pub fn memory(&self) -> Memory {
  - self.with_context_data(|context| {
  - let ptr = context
  + self.with_context_data(|context_data| {
  + let instance_ptr = context_data
  .wasmer_instance
  .expect("Wasmer instance is not set. This is a bug.");
  - let instance = unsafe { ptr.as_ref() };
  + let instance = unsafe { instance_ptr.as_ref() };
  let mut memories: Vec<Memory> = instance
  .exports
  .iter()
  