Jenkins 1.651.3
Log Parser Plugin 2.0
Pipeline 2.4

Log parser plugin does not throw an exception after detecting errors in console output.
The plugin fails the build but there is no way to know in runtime if it was failed.
 

try {
    step([$class: 'LogParserPublisher', 
        failBuildOnError: true, 
        parsingRulesPath: 'blabla.txt', 
        showGraphs: true, 
        unstableOnWarning: true, 
        useProjectRule: false])
} catch(e) {
    echo 'Check console output for errors.'
} finally {
    echo 'finally'
}

So the output 'Check console output for errors.' is not seen. At the same time 'finally' block is executed and output is seen in console log.