fix some nits

prodigy_pdf/__init__.py

@@ -8,8 +8,8 @@
 import pypdfium2 as pdfium
 
 from prodigy import recipe, set_hashes, ControllerComponentsDict
-from prodigy.components.stream import Stream
-from prodigy.util import msg
+from prodigy.components.stream import Stream, get_stream
+from prodigy.util import msg, split_string
 
 
 def page_to_image(page: pdfium.PdfPage) -> str:
@@ -132,7 +132,7 @@ def _validate_ocr_example(ex: Dict):
     # fmt: off
     dataset=("Dataset to save answers to", "positional", None, str),
     source=("Source with PDF Annotations", "positional", None, str),
-    labels=("Labels to consider", "option", "l", str),
+    labels=("Labels to consider", "option", "l", split_string),
     scale=("Zoom scale. Increase above 3 to upscale the image for OCR.", "option", "s", int),
     remove_base64=("Remove base64-encoded image data", "flag", "R", bool),
     fold_dashes=("Removes dashes at the end of a textline and folds them with the next term.", "flag", "f", bool),
@@ -150,11 +150,10 @@ def pdf_ocr_correct(
 ) -> ControllerComponentsDict:
     """Applies OCR to annotated segments and gives a textbox for corrections."""
     stream = get_stream(source)
-    labels = labels.split(",")
 
     def new_stream(stream):
         for ex in stream:
-            useful_spans = [span for span in ex['spans'] if span['label'] in labels]
+            useful_spans = [span for span in ex.get('spans', []) if span['label'] in labels]
             if useful_spans:
                 _validate_ocr_example(ex)
                 pdf = pdfium.PdfDocument(ex['meta']['path'])