PDFReport fails when no coverage data available.

code]
[INFO] ------------------------------------------------------------------------
[ERROR] FATAL ERROR
[INFO] ------------------------------------------------------------------------
[INFO] ExceptionConverter: java.lang.RuntimeException: 1 annotations had invalid placement pages.
[INFO] ------------------------------------------------------------------------
[INFO] Trace
/tmp/plexus-resources1304268035tmp:20: ExceptionConverter: java.lang.RuntimeException: 1 annotations had invalid placement pages.
at org.apache.tools.ant.Task.perform(Task.java:373)
at org.apache.tools.ant.Target.execute(Target.java:341)
at org.apache.tools.ant.Target.performTasks(Target.java:369)
at org.apache.tools.ant.Project.executeSortedTargets(Project.java:1216)
at org.apache.tools.ant.Project.executeTarget(Project.java:1185)
at com.atlassian.maven.plugin.clover.CloverReportMojo.createReport(CloverReportMojo.java:343)