YQL-19397 Fix tiny bug in Re2

commit_hash:5e0947e4fbecc6de20eac2f987e45849f1755448

yql/essentials/udfs/common/re2/re2_udf.cpp

@@ -217,7 +217,7 @@ namespace {
                         StringPiece text(piece);
                         std::vector<TUnboxedValue> matches;
                         for (StringPiece w; text.begin() < text.end() && RE2::FindAndConsume(&text, *Regexp, &w);) {
-                            if (w.size() == 0) {
+                            if (w.size() == 0 && !text.empty()) {
                                 text.remove_prefix(1);
                             }
                             matches.emplace_back(valueBuilder->SubString(args[0], std::distance(piece.begin(), w.begin()), w.size()));