aeron-client/src/main/java/io/aeron/CommonContext.java
public int saveErrorLog(final PrintStream out)
    {
        final MappedByteBuffer cncByteBuffer = mapExistingCncFile(null);
        try
        {
            return saveErrorLog(out, cncByteBuffer);
        }
        finally
        {
            IoUtil.unmap(cncByteBuffer);
        }
    }
public int saveErrorLog(final PrintStream out)
    {
        final MappedByteBuffer cncByteBuffer = mapExistingCncFile(null);
        try
        {
            return saveErrorLog(out, cncByteBuffer);
        }
        finally
        {
            IoUtil.unmap(cncByteBuffer);
        }
    }
Read the error log to a given {@link PrintStream}

@param out to write the error log contents to.
@return the number of observations from the error log.