Raise ParseError, not StopIteration, from readOne on an empty stream

tests/test_vobject_parsing.py

@@ -143,6 +143,16 @@ def test_bad_stream():
         vobject.base.readOne(bad_stream)
 
 
+def test_empty_stream():
+    """
+    An empty or whitespace-only stream has no components and used to raise a
+    bare StopIteration; it should raise ParseError.
+    """
+    for stream in ("", "   ", "\n\n\t"):
+        with pytest.raises(vobject.base.ParseError):
+            vobject.base.readOne(stream)
+
+
 def test_bad_line():
     """
     Test bad line in ics file

vobject/base.py

@@ -1122,7 +1122,12 @@ def readOne(stream, validate=False, transform=True, ignoreUnreadable=False, allo
     """
     Return the first component from stream.
     """
-    return next(readComponents(stream, validate, transform, ignoreUnreadable, allowQP))
+    try:
+        return next(readComponents(stream, validate, transform, ignoreUnreadable, allowQP))
+    except StopIteration:
+        # An empty (or whitespace-only) stream yields no components; report it
+        # as a parse error instead of letting a bare StopIteration escape.
+        raise ParseError("No components in stream")
 
 
 # --------------------------- version registry ---------------------------------