ProcessState::addErrorContextValue() raises a TypeError that hides the real problem (empty iterables, PropertySetterTask) #203

Description

ProcessState::addErrorContextValue() only accepts string|int|array values. When a task passes any other value (null, bool, float, object), a \TypeError is thrown and the real behaviour or error is lost:

• Iterable tasks on an empty iterable (ConstantIterableOutputTask, InputIteratorTask, YamlReaderTask with {}/[], SplitJoinLineTask with no line to produce): AbstractIterableOutputTask::execute() always adds iterator_key before checking the iterator. On an empty iterator key() is null, so the process fails instead of skipping the task, as documented.
• PropertySetterTask: when a value cannot be set, the task adds the value to the error context. If that value is a bool, float, null or object, the TypeError replaces the original exception (e.g. NoSuchPropertyException).

Reproduction

clever_age_process:
    configurations:
        demo.error_context.empty_iterable:
            tasks:
                iterate:
                    service: '@CleverAge\ProcessBundle\Task\ConstantIterableOutputTask'
                    options:
                        output: []
                    outputs: [debug]
                debug:
                    service: '@CleverAge\ProcessBundle\Task\Debug\DebugTask'

        demo.error_context.property_setter:
            tasks:
                entry:
                    service: '@CleverAge\ProcessBundle\Task\ConstantOutputTask'
                    options:
                        output:
                            name: Foo
                    outputs: [set]
                set:
                    service: '@CleverAge\ProcessBundle\Task\PropertySetterTask'
                    options:
                        values:
                            enabled: true # property path on an array: cannot be written
                    outputs: [debug]
                debug:
                    service: '@CleverAge\ProcessBundle\Task\Debug\DebugTask'

$ bin/console cleverage:process:execute demo.error_context.empty_iterable
CRITICAL  [cleverage_process_task] CleverAge\ProcessBundle\Model\ProcessState::addErrorContextValue(): Argument #2 ($value) must be of type array|string|int, null given, called in /var/www/vendor/cleverage/process-bundle/src/Task/AbstractIterableOutputTask.php on line 33

$ bin/console cleverage:process:execute demo.error_context.property_setter
CRITICAL  [cleverage_process_task] CleverAge\ProcessBundle\Model\ProcessState::addErrorContextValue(): Argument #2 ($value) must be of type array|string|int, true given, called in /var/www/vendor/cleverage/process-bundle/src/Task/PropertySetterTask.php on line 42 ["property" => "enabled"]

Expected: the first process succeeds with no output, the second one reports Cannot write property "enabled" to an array. Maybe you should write the property path as "[enabled]" instead?. Tested on main (c1a2804), PHP 8.5, Symfony 7.4.

Cause

• ProcessState::addErrorContextValue() types $value as string|int|array, while setErrorContext(array) accepts any value, and the context is only passed to the PSR-3 logger, which accepts anything.
• AbstractIterableOutputTask::execute() adds iterator_key before valid() is checked.
• PropertySetterTask::execute() adds the configured value, which can be of any type.

Proposed fix

• Widen the $value parameter of ProcessState::addErrorContextValue() to mixed.
• In AbstractIterableOutputTask::execute(), add iterator_key only when the iterator is valid: an empty iterable then produces no output and the task is skipped.
• Update the reference documentation (property_setter_task.md, yaml_reader_task.md, split_join_line_task.md, 03-custom_tasks.md), add unit tests.

Requirements

• Documentation updates
  • Reference
  • Cookbooks
  • Changelog
• Unit tests

Breaking changes

None for callers. Widening a parameter type is backward compatible, except for a subclass of ProcessState overriding addErrorContextValue() with the old signature (it must widen $value to mixed).