message: replace panics with return Err()
diff: @@ -634,7 +634,7 @@ fn execute_wasm(options: &Run) -> Result<(), String> {
  if let Err(ref err) = result {
  match err {
  - RuntimeError::Trap { msg } => panic!("wasm trap occured: {}", msg),
  + RuntimeError::Trap { msg } => return Err(format!("wasm trap occured: {}", msg)),
  #[cfg(feature = "wasi")]
  RuntimeError::Error { data } => {
  if let Some(error_code) = data.downcast_ref::<wasmer_wasi::ExitCode>() {
  @@ -644,7 +644,7 @@ fn execute_wasm(options: &Run) -> Result<(), String> {
  #[cfg(not(feature = "wasi"))]
  RuntimeError::Error { .. } => (),
  }
  - panic!("error: {:?}", err)
  + return Err(format!("error: {:?}", err))
  }
  }
  } else {
  