AR: When plugin is run on job with no Sonar execution configured the next exception occurs (see below).
ER: Build should be marked as failed; human-readable error message should be present instead of exception stacktrace.

at java.io.FileInputStream.open(Native Method)
at java.io.FileInputStream.<init>(FileInputStream.java:138)
at hudson.FilePath.read(FilePath.java:1738)
at hudson.FilePath.readToString(FilePath.java:1767)
at org.jenkinsci.plugins.sonargerrit.SonarToGerritBuilder.perform(SonarToGerritBuilder.java:137)
at hudson.tasks.BuildStepMonitor$1.perform(BuildStepMonitor.java:20)
at hudson.model.AbstractBuild$AbstractBuildExecution.perform(AbstractBuild.java:770)
at hudson.maven.MavenModuleSetBuild$MavenModuleSetBuildExecution.build(MavenModuleSetBuild.java:909)
at hudson.maven.MavenModuleSetBuild$MavenModuleSetBuildExecution.doRun(MavenModuleSetBuild.java:860)
at hudson.model.AbstractBuild$AbstractBuildExecution.run(AbstractBuild.java:533)
at hudson.model.Run.execute(Run.java:1745)
at hudson.maven.MavenModuleSetBuild.run(MavenModuleSetBuild.java:529)
at hudson.model.ResourceController.execute(ResourceController.java:89)
at hudson.model.Executor.run(Executor.java:240)