Description

This PR fixes a critical observability and memory management issue in the hyperf/tracer component when tracing coroutines (CoroutineAspect).

Motivation

Currently, if a coroutine executed via Co::create() throws an unhandled exception or is abruptly terminated, the tracer span is never finished ($child->finish()) and never flushed ($tracer->flush()).
This causes three main issues:

1. Memory Leaks: Unflushed spans remain in the worker's memory buffer.
2. Incomplete Traces: Orphaned spans that disappear from tracing UI (Jaeger/Zipkin).
3. Missing Error Context: Exceptions happening inside the coroutine are not tagged (error=true) in the span, making troubleshooting difficult.

Changes made

• Wrapped the callable execution in a try/catch/finally block to capture exceptions, add the error tag, and log the exception details to the span.
• Implemented Co::defer as a fallback to guarantee the span is closed even if the coroutine lifecycle is interrupted by flow-control functions like Co::exit().
• Used a lightweight \stdClass object to keep track of the span's finished state. This prevents multiple executions of finish()/flush() and avoids using variable references (&$finished) inside closures, which is a known anti-pattern in Swoole and triggers static analysis warnings.

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)