thrown Exceptions are hidden when serializing complex objects with a handler

[Hikariii]

Q	A
Bug report?	yes
Feature request?	no
BC Break report?	no
RFC?	no

The try/finally block in the SerializationGraphNavigator making sure the context visitingStack is working correctly hides all Exceptions thrown in handlers when the context has started visiting a (nested) object but has not stopped visiting is.
This is the case in many situations where a handler (like the ArrayCollectionHandler) is used to serialize a more complex object (or object with objects).

Code hiding the exception is this one:
https://github.com/schmittjoh/serializer/blob/3.5.0/src/GraphNavigator/SerializationGraphNavigator.php#L196-L200
This is because finally is executed before the Exception is thrown and the stopVisiting() causes an other Exception to be thrown, hiding the first Exception.

Running stopVisiting() first is sometimes necessary

The commit that introduced this change makes it clear it is created for a specific situation where serializing NULL throws an exception: ffc0fee

The fact that this NotAcceptableException is needed is also mentioned in the UPGRADING guide: https://github.com/schmittjoh/serializer/blame/3.5.0/UPGRADING.md#L56-L57

Steps required to reproduce the problem

1. Use a custom serializationHandler and serialize object data with it.
2. In the handler start visiting a (nested) object, changing the visiting stack of the context.
3. Throw an exception while the visiting stack is visiting this nested object.

Expected Result

• The exception thrown while parsing the compex serialization structure is shown.

Actual Result

• The exception thrown is an error about the visitingStack not working well:

RuntimeException('Context visitingStack not working well');

[goetas]

Thanks for working on this. I think that is something we should fix.

[goetas]

fixed in #1169