devalue is too strict about what can be serialized with custom types

[Janpot]

Trying to add some custom types for functions but devalue seems to throw before calling the replacer. I understand that serializing functions is a non-goal, but I'm not sure it makes sense to prevent the following use-cases to be implemented with custom types:

• Reviving a pure function using a custom type. There is no transferring of the function, we can just reference it on both sides of serialization:

  const add = (a, b) => a + b;
  
  const stringified = devalue.stringify({ myOperation: add }, { Add: (value) => value === add });
  
  const result = devalue.parse(stringified, { Add: () => add });
  
  console.log(result.myOperation(1, 2));

• Ignoring non-serializable. While transferring user generated values, trying to do a best effort while communicating failures:

  const NONTRANSFERRABLE = Symbol('nontransferrable');
  
  const stringified = devalue.stringify(
  { foo: () => 1 },
  { Ignore: (value) => typeof value === 'function' || value === NONTRANSFERRABLE },
  );
  
  const result = devalue.parse(stringified, { Ignore: () => NONTRANSFERRABLE });
  
  console.log(result.add(1, 2));

both of these result in

Uncaught DevalueError: Cannot stringify a function

Would you consider relaxing the acceptable values that can be serialized with custom types?

[phi-bre]

I think this can be closed since #123 was merged