diff --git a/spacy/pipeline/span_predictor.py b/spacy/pipeline/span_predictor.py
index 12ea6611c..d21a45edb 100644
--- a/spacy/pipeline/span_predictor.py
+++ b/spacy/pipeline/span_predictor.py
@@ -96,7 +96,7 @@ class SpanPredictor(TrainablePipe):
         self.input_prefix = input_prefix
         self.output_prefix = output_prefix
 
-        self.cfg = {}
+        self.cfg: Dict[str, Any] = {}
 
     def predict(self, docs: Iterable[Doc]) -> List[MentionClusters]:
         # for now pretend there's just one doc
@@ -205,7 +205,7 @@ class SpanPredictor(TrainablePipe):
         ops = self.model.ops
 
         # NOTE This is doing fake batching, and should always get a list of one example
-        assert len(examples) == 1, "Only fake batching is supported."
+        assert len(list(examples)) == 1, "Only fake batching is supported."
         # starts and ends are gold starts and ends (Ints1d)
         # span_scores is a Floats3d. What are the axes? mention x token x start/end
         for eg in examples: