fix: Patch OpenTelemetry to handle None tokens (#18498)

Signed-off-by: -LAN- <laipz8200@outlook.com>

api/app_factory.py

         ext_mail,
         ext_migrate,
         ext_otel,
+        ext_otel_patch,
         ext_proxy_fix,
         ext_redis,
         ext_repositories,
         ext_proxy_fix,
         ext_blueprints,
         ext_commands,
+        ext_otel_patch,  # Apply patch before initializing OpenTelemetry
         ext_otel,
     ]
     for ext in extensions:

api/extensions/ext_otel_patch.py

+"""
+Patch for OpenTelemetry context detach method to handle None tokens gracefully.
+
+This patch addresses the issue where OpenTelemetry's context.detach() method raises a TypeError
+when called with a None token. The error occurs in the contextvars_context.py file where it tries
+to call reset() on a None token.
+
+Related GitHub issue: https://github.com/langgenius/dify/issues/18496
+
+Error being fixed:
+```
+Traceback (most recent call last):
+  File "opentelemetry/context/__init__.py", line 154, in detach
+    _RUNTIME_CONTEXT.detach(token)
+  File "opentelemetry/context/contextvars_context.py", line 50, in detach
+    self._current_context.reset(token)  # type: ignore
+    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+TypeError: expected an instance of Token, got None
+```
+
+Instead of modifying the third-party package directly, this patch monkey-patches the
+context.detach method to gracefully handle None tokens.
+"""
+
+import logging
+from functools import wraps
+
+from opentelemetry import context
+
+logger = logging.getLogger(__name__)
+
+# Store the original detach method
+original_detach = context.detach
+
+
+# Create a patched version that handles None tokens
+@wraps(original_detach)
+def patched_detach(token):
+    """
+    A patched version of context.detach that handles None tokens gracefully.
+    """
+    if token is None:
+        logger.debug("Attempted to detach a None token, skipping")
+        return
+
+    return original_detach(token)
+
+
+def is_enabled():
+    """
+    Check if the extension is enabled.
+    Always enable this patch to prevent errors even when OpenTelemetry is disabled.
+    """
+    return True
+
+
+def init_app(app):
+    """
+    Initialize the OpenTelemetry context patch.
+    """
+    # Replace the original detach method with our patched version
+    context.detach = patched_detach
+    logger.info("OpenTelemetry context.detach patched to handle None tokens")