No NullPointerException on the logs

I have a strange behaviour in my java code I would like to ask some advice.
In a multithreading application I wrote this code:

scratchDir.resolve(directoryTree).toFile().mkdirs();

For a bug the Object scratchDir is null, I was expecting a stack trace on the logs but there's nothing about the error.
I have checked the code and I never try to catch the NullPointerException.

Here is the complete method code:

    @Override
    public void write(JsonObject jsonObject) throws FileSystemException {
        Path directoryTree = getRelativePath();
        scratchDir.resolve(directoryTree).toFile().mkdirs();
        String newFileName = getHashFileName(jsonObject);
        Path filePath = scratchDir.resolve(directoryTree).resolve(newFileName);
        logger.debug("Write new file Json {} to persistent storage dir {}", newFileName, scratchDir);
        File outputFile = filePath.toFile();
        if (outputFile.exists()) {
            throw new FileAlreadyExistsException(filePath.toString());
        }
        try (FileWriter fileWriter = new FileWriter(outputFile)) {
            fileWriter.write(jsonObject.toString());
            fileWriter.flush();
        } catch (Exception e) {
            logger.error(e);
        }
    }

Why I don't have the exception in my logs?

Why are you doing this?

The proper way to do this is:

Files.createDirectories(scratchDir.resolve(directoryTree));

don't mix old and new API. The old mkdirs() api DEMANDS that you check the return value; if it is false, the operation failed, and you do not get the benefit of an exception to tell you why. This is the primary reason for why there is a new API in the first place.

Are you sure you aren't confused - and that is the actual problem? The line as you have it will happily do absolutely nothing whatsoever (no directories, and no logs or exceptions). The line above will throw if it can't make the directories, so start there.

Then, if that line IS being run and nothing is logged, then you've caught the NPE and discarded it, someplace you didn't paste.