[Agent][Platform] Transform Serializer into a domain exception

[VincentLanglet]

Currently there is two call to serializer

• one in ToolResultConverter

  ai/src/agent/src/Toolbox/ToolResultConverter.php

  Line 43 in 5242431

  return $this->serializer->serialize($result, 'json');

• one in AgentProcessor

  ai/src/agent/src/StructuredOutput/AgentProcessor.php

  Line 108 in 5242431

  $this->serializer->deserialize($output->getResult()->getContent(), $this->outputStructure, 'json')

One issue is the fact,

• Those call might throw exception (I recently got a MissingConstructorArgumentsException because the AI call didn't return the expected format of data)
• Those exception are not documented anywhere
  • ToolResultConverter::convert has no throws tag, so does Toolbox\AgentProcessor::processOutput
  • AgentProcessor::processOutput has no throws tag

What could be interesting if you agree with @chr-hertel @OskarStark would be

• To try/catch those call in order to throw an exception from symfony/agent
• To document the processOutput that such exception could be thrown

Basically InputProcessorInterface::processInput and OutputProcessorInterface::processOutput should be restricted to throws Symfony\AI\Agent\Exception\ExceptionInterface only.

[VincentLanglet]

I'll be happy working on the PR if you agree with this issue @OskarStark @chr-hertel

[chr-hertel]

Yes, makes sense to me - be aware of #802 tho