fix type again

Author: sentrivana

sentry_sdk/integrations/opentelemetry/sampler.py

@@ -59,6 +59,9 @@ def get_parent_sample_rate(parent_context, trace_id):
 
     if is_span_context_valid and parent_context.trace_id == trace_id:
         parent_sample_rate = parent_context.trace_state.get(TRACESTATE_SAMPLE_RATE_KEY)
+        if parent_sample_rate is None:
+            return None
+
         try:
             return float(parent_sample_rate)
         except Exception: