PHPLIB-1679 Call DocumentCodec::encode() only on objects

[GromNaN]

Fix PHPLIB-1679

• Check if the input document is an object before calling DocumentCodec::encode()
• Never validate the value returned by DocumentCodec::encode() as the type MongoDB\BSON\Document is enforced.

[GromNaN]

I should add tests, probably in CodecCollectionFunctionalTest.

[alcaeus]

I don't think we should add the error checks here. The template annotation on the DocumentCodec requires an object type as input for encode, but the idea is that the codecs accept any value and throw the invalidEncodableValue exception themselves if they cannot encode the value - that is unless one uses encodeIfSupported.

I wonder if we should instead document the parameter as mixed in the encode and decode methods in DocumentCodec (and potentially in Encoder and Decoder as well) as the methods can be called with the wrong input type but will simply throw an exception if it's not of the expected type. Not sure if we can represent that with static analysis annotations.

[GromNaN]

What I understand is that calling DocumentCodec::encode() with something other than an object of the class it can encode is an error: the DocumentCodec implementation must throw an exception at runtime in this case. But by no means a normal use case. UnsupportedValueException is a child of LogicException, meaning that's an error in the code.

LogicException that represents error in the program logic. This kind of exception should directly lead to a fix in your code.

The @psalm-param ObjectType $value annotation clearly shows the intention. I don't see why we should make static analysis less capable of detecting errors by not specifying the expected value type.

Throwing the error before or inside DocumentCodec::encode() will result in the same exception to be thrown.