Remove unnecessary warning when (not) setting status description

Currently we log a warning that status description should only be set
for an error condition even when description is not being set. This
commit silences such warnings.

opentelemetry-api/src/opentelemetry/trace/status.py

@@ -49,15 +49,15 @@ def __init__(
         self._status_code = status_code
         self._description = None
 
-        if description is not None and not isinstance(description, str):
-            logger.warning("Invalid status description type, expected str")
-            return
-
-        if status_code is not StatusCode.ERROR:
-            logger.warning(
-                "description should only be set when status_code is set to StatusCode.ERROR"
-            )
-            return
+        if description:
+            if not isinstance(description, str):
+                logger.warning("Invalid status description type, expected str")
+                return
+            if status_code is not StatusCode.ERROR:
+                logger.warning(
+                    "description should only be set when status_code is set to StatusCode.ERROR"
+                )
+                return
 
         self._description = description
 

opentelemetry-api/tests/trace/test_status.py

@@ -30,8 +30,8 @@ def test_constructor(self):
 
     def test_invalid_description(self):
         with self.assertLogs(level=WARNING) as warning:
-            status = Status(description={"test": "val"})  # type: ignore
-            self.assertIs(status.status_code, StatusCode.UNSET)
+            status = Status(status_code=StatusCode.ERROR, description={"test": "val"})  # type: ignore
+            self.assertIs(status.status_code, StatusCode.ERROR)
             self.assertEqual(status.description, None)
             self.assertIn(
                 "Invalid status description type, expected str",