Java parallelStream() IllegalArgumentException sometimes prints exception name in message

Question

I am parsing a CSV file using parallelStream() and have noticed some odd behaviour. The code in question is here:

public List<AddressRaw> parseAddress(List<CSVRecord> records) {

    return records.subList(1, records.size())
            .parallelStream()
            .flatMap(record -> {

                // There should only be 10 columns in the CSV
                if (record.size() > 10) {
                    log.error("Too many columns were detected on row number " + record.getRecordNumber());
                    throw new IllegalArgumentException("Too many columns were detected on row number " + record.getRecordNumber());
                }

The controller where I call the above method:

 try {
        // csv files are identified by either text/csv or application/vnd.ms-excel
        if (file.isEmpty() || Objects.isNull(file.getContentType()) || !(file.getContentType().equals("text/csv") || file.getContentType().equals("application/vnd.ms-excel"))) {
            log.error("File uploaded is not a csv");
            throw new BadRequestException("File uploaded is not a csv");
        }

        List<CSVRecord> records = CSVHelper.recordsFromBytes(file.getBytes());

        // convert the rows into a format mirroring a db transit time
        List<AddressRaw> rawAddresss = addressService.parseAddress(records);
        if (rawAddresss.isEmpty()) {
            throw new BadRequestException("No addresses found");
        }

        // execute the upsert in batches (Upserts count as two changes, as the insert fails then an update occurs)
        Integer addressesInserted = addressService.batchInsertAddresses(rawAddresss, targetUserId);

        LocalDateTime end = LocalDateTime.now();
        log.info("Upserted {} AddressRaw records in: {}ms", addressesInserted, start.until(end, ChronoUnit.MILLIS));

        return ResponseEntity.ok(addressesInserted);
    } catch (IOException e) {
        log.error("Unable to parse csv file: ", e);
    } catch (DataAccessException e) {
        log.error("Unable to execute SQL: ", e);
    }

Sometimes the error that I get in the frontend is "Too many columns were detected on row number 3" for example, which is what I would expect. Sometimes the error I get is "java.lang.IllegalArgumentException: Too many columns were detected on row number 3" and I'm not exactly sure why it prints off the exception name as well? Is there something I am missing here?