message: Make contract runtime return the proper error type
diff: @@ -4,7 +4,6 @@ mod config;
  pub use config::Config;
  use std::{
  - convert::Infallible,
  fmt::{self, Debug, Display, Formatter},
  sync::Arc,
  time::Instant,
  @@ -146,7 +145,7 @@ where
  REv: From<Event> + Send,
  {
  type Event = Event;
  - type ConstructionError = Infallible;
  + type ConstructionError = ConfigError;
  fn handle_event(
  &mut self,
  