message: Fix `value` unit tests where `assert!` was not applied
diff: @@ -614,7 +614,7 @@ mod tests {
  macro_rules! null_test {
  ($op: ident $a: expr, $b: expr) => {
  - matches!($a.$op(&$b), Ok(Null));
  + assert!($a.$op(&$b).unwrap().is_null());
  };
  }
  @@ -789,7 +789,7 @@ mod tests {
  assert_eq!(a.concat(&I64(1)), Str("A1".to_owned()));
  assert_eq!(a.concat(&F64(1.0)), Str("A1".to_owned()));
  assert_eq!(I64(2).concat(&I64(1)), Str("21".to_owned()));
  - matches!(a.concat(&Null), Null);
  + assert!(a.concat(&Null).is_null());
  }
  #[test]
  