Fix worker-pool crash on tokens with whitespace surface forms

A token whose FORM is whitespace (e.g. a lone space) collapsed the
tab-separated CoNLL-U line under str.split(), leaving 9 fields instead
of 10 and raising IndexError on the score column in CoNLLUP_Token. The
exception was uncaught and killed the whole streaming process, so
korapxmltool's worker pool saw a broken pipe, re-queued the in-flight
documents, and re-crashed on the same poisoned input until every worker
died -- observed as running threads dropping off one-by-one after tens
of thousands of texts.

CoNLLUP_Token now parses on the tab delimiter (preserving whitespace
FORM columns), falls back to whitespace splitting for space-delimited
input, and pads short lines to the 10 CoNLL-U columns. As
defense-in-depth, a parse/annotation failure for a single document is
now logged and skipped while still echoing its # eot/# eof marker, so
one bad document can no longer take down the run.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Change-Id: I99b96a1ce21e23c1ebb3775afec4c3014d4e9253
diff --git a/systems/parse_spacy_pipe.py b/systems/parse_spacy_pipe.py
index 0432709..33f47de 100644
--- a/systems/parse_spacy_pipe.py
+++ b/systems/parse_spacy_pipe.py
@@ -367,10 +367,19 @@
 	# still processed in CHUNK_SIZE-bounded blocks and streamed out.
 	last_log_time = start
 	for block_lines, terminator in iter_documents(stdin, CHUNK_SIZE):
-		annos, _ = read_conll(iter(block_lines), 0, token_class=token_class, comment_str=args.comment_str, our_foundry="spacy")
-		if annos:
-			dependency_warnings += annotate(annos, total_processed_sents)
-			total_processed_sents += len(annos)
+		# Never let one malformed document take down the whole stream: a parse
+		# or annotation failure here would otherwise crash the process, break
+		# the pipe, and make korapxmltool's worker pool re-queue and re-crash on
+		# the same poisoned input until every worker dies. Log it, skip the
+		# document, and still echo the protocol marker below so the worker pool
+		# releases its in-flight slot.
+		try:
+			annos, _ = read_conll(iter(block_lines), 0, token_class=token_class, comment_str=args.comment_str, our_foundry="spacy")
+			if annos:
+				dependency_warnings += annotate(annos, total_processed_sents)
+				total_processed_sents += len(annos)
+		except Exception as doc_error:
+			logger.error(f"Skipping document after failure ({terminator or 'chunk'}): {str(doc_error)}")
 
 		# Echo the protocol marker back so korapxmltool can pair the output with
 		# the source document and release the in-flight buffer slot, then flush