Update langfuse/_client/client.py

Co-authored-by: greptile-apps[bot] <165735046+greptile-apps[bot]@users.noreply.github.com>

Author: hassiebp

langfuse/_client/client.py

@@ -165,6 +165,8 @@ def __init__(
         self._mask = mask
         self._project_id = None
         sample_rate = sample_rate or float(os.environ.get(LANGFUSE_SAMPLE_RATE, 1.0))
+        if not 0.0 <= sample_rate <= 1.0:
+            raise ValueError(f"Sample rate must be between 0.0 and 1.0, got {sample_rate}")
 
         self._tracing_enabled = (
             tracing_enabled