Simplify attr adding code and remove unnecessary guards.

These are type-checked anyway.

Author: sstanovnik

pydantic_ai_slim/pydantic_ai/agent/__init__.py

@@ -717,14 +717,11 @@ def _run_span_end_attributes(
                 attrs['pydantic_ai.variable_instructions'] = True
 
         extra_attributes: dict[str, str] = {}
-        span_attrs_setting = settings.span_attributes
-        if span_attrs_setting:
-            if callable(span_attrs_setting):
-                resolved_attrs = span_attrs_setting(run_ctx)
-                if resolved_attrs:
-                    extra_attributes = dict(resolved_attrs)
+        if settings.span_attributes:
+            if callable(settings.span_attributes):
+                extra_attributes = settings.span_attributes(run_ctx)
             else:
-                extra_attributes = dict(span_attrs_setting)
+                extra_attributes = settings.span_attributes
 
         return {
             **usage.opentelemetry_attributes(),