AccessLogSampler returns error result when EOF is reached

**Oleg Gorobets** ([Bug 60922](https://bz.apache.org/bugzilla//show_bug.cgi?id=60922&redirect=false)):
AccessLogSampler returns "error result" when EOF is reached. See AccessLogSampler on line 169:

return errorResult(new Error("No entries found"), new HTTPSampleResult());

This behavior results in that this result is then passed to listeners and the following weird line is generated in the summary report:

1970-01-01 02:00:00.000,0,,Non HTTP response code: java.lang.Error,Non HTTP response message: No entries found,Thread Group 1-1,text,false,,520,0,1,1,0,0,0

This case is not an error. There should be null instead of "error result" or other type of result indicating there is no more data for this file.

Severity: normal
OS: All