The new ECJ parser can still fail on some occasions, depending of the content of the code it analyzes, and depending of the recovery mechanism it can trigger.
When encountering such situations, SonarJava should be able to recover and NOT fail analysis, except if property "sonar.java.failOnException" is set to true. In the meantime, the property (hidden, not documented, and not used in PEACH) should be renamed to "sonar.internal.analysis.failFast" in order to match with other analyzers.
Similarly, issue filters, which are applied every time an issue is raised, can fail in the process of filtering. If it's the case, then the whole analysis should not fail except if the property is set to true.