NPE when goal is invalid in custom lifecycle.xml file

If I have (notice the goal that is incorrectly prefixed by "clover:"):

<lifecycles>
<lifecycle>
<id>clover</id>
<phases>
<phase>
<id>generate-sources</id>
<executions>
<execution>
<configuration>
<outputDirectory>${project.build.directory}/clover</outputDirectory>
</configuration>
<goals>
<goal>clover:instrument</goal>
</goals>
</execution>
</executions>
</phase>
</phases>
</lifecycle>
</lifecycles>

Then I get:

java.lang.NullPointerException
at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoals(DefaultLifecycleExecutor.java:162)
at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoalWithLifecycle(DefaultLifecycleExecutor.java:143)
at org.apache.maven.lifecycle.DefaultLifecycleExecutor.forkLifecycle(DefaultLifecycleExecutor.java:227)
at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoals(DefaultLifecycleExecutor.java:164)
at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoalWithLifecycle(DefaultLifecycleExecutor.java:143)

... which is not very explicit...