message: replace expect with map_err
diff: @@ -525,20 +525,21 @@ fn execute_wasm(options: &Run) -> Result<(), String> {
  args.push(Value::I32(x));
  }
  - let index = instance
  - .resolve_func("_start")
  - .expect("The loader requires a _start function to be present in the module");
  + let index = instance.resolve_func("_start").map_err(|_| {
  + format!("The loader requires a _start function to be present in the module")
  + })?;
  +
  let mut ins: Box<dyn LoadedInstance<Error = String>> = match loader {
  LoaderName::Local => Box::new(
  instance
  .load(LocalLoader)
  - .expect("Can't use the local loader"),
  + .map_err(|e| format!("Can't use the local loader: {:?}", e))?,
  ),
  #[cfg(feature = "loader-kernel")]
  LoaderName::Kernel => Box::new(
  instance
  .load(::wasmer_kernel_loader::KernelLoader)
  - .expect("Can't use the kernel loader"),
  + .map_err(|e| format!("Can't use the local loader: {:?}", e))?,
  ),
  };
  println!("{:?}", ins.call(index, &args));
  @@ -610,7 +611,7 @@ fn execute_wasm(options: &Run) -> Result<(), String> {
  f.read_to_end(&mut out).unwrap();
  Some(
  wasmer_runtime_core::state::InstanceImage::from_bytes(&out)
  - .expect("failed to decode image"),
  + .map_err(|_| format!("failed to decode image"))?,
  )
  } else {
  None
  