CompactionAwareWriter_getWriteDirectory throws incompatible exceptions

public Directories.DataDirectory getWriteDirectory(Iterable<SSTableReader> sstables, long estimatedWriteSize)
    {
        File directory = null;
        for (SSTableReader sstable : sstables)
        {
            if (directory == null)
                directory = sstable.descriptor.directory;
            if (!directory.equals(sstable.descriptor.directory))
            {
                logger.trace("All sstables not from the same disk - putting results in {}", directory);
                break;
            }
        }
        Directories.DataDirectory d = getDirectories().getDataDirectoryForFile(directory);
        if (d != null)
        {
            long availableSpace = d.getAvailableSpace();
            if (availableSpace < estimatedWriteSize)
                throw new RuntimeException(String.format("Not enough space to write %s to %s (%s available)",
                                                         FBUtilities.prettyPrintMemory(estimatedWriteSize),
                                                         d.location,
                                                         FBUtilities.prettyPrintMemory(availableSpace)));
            logger.trace("putting compaction results in {}", directory);
            return d;
        }
        d = getDirectories().getWriteableLocation(estimatedWriteSize);
        if (d == null)
            throw new RuntimeException(String.format("Not enough disk space to store %s",
                                                     FBUtilities.prettyPrintMemory(estimatedWriteSize)));
        return d;
    }

protected Directories.DataDirectory getWriteDirectory(long writeSize)
    {
        Directories.DataDirectory directory = getDirectories().getWriteableLocation(writeSize);
        if (directory == null)
            throw new RuntimeException("Insufficient disk space to write " + writeSize + " bytes");

        return directory;
    }

protected Directories.DataDirectory getWriteDirectory(long writeSize)
    {
        Directories.DataDirectory directory = getDirectories().getWriteableLocation(writeSize);
        if (directory == null)
            throw new FSWriteError(new IOException("Insufficient disk space to write " + writeSize + " bytes"), "");

        return directory;
    }