Pulling Build Error/Important Logs

Is there a way to extract only Important or Error messages from a build log?

I know of these two endpoints:

http://teamcity:8111/app/rest/problemOccurrences?locator=build:(BUILD_LOCATOR)

But this only gives problem type (i.e. test, exit code etc)

http://teamcity:8111/httpAuth/downloadBuildLog.html?buildId=.

But this downloads the whole build log.

Is there an api endpoint for this case or is there any identifier I can use in the build log to extract only important/error logs?