Report with addEnvInfo activated runs into a NPE

The report generator runs into a NPE if the addEnvInfo property is set to 'true' and no property element is set.

java.lang.NullPointerException
at de.smartics.maven.plugin.buildmetadata.BuildReportRenderer.getLabel(BuildReportRenderer.java:424)
at de.smartics.maven.plugin.buildmetadata.BuildReportRenderer.renderCell(BuildReportRenderer.java:313)
at de.smartics.maven.plugin.buildmetadata.BuildReportRenderer.renderNonStandardProperties(BuildReportRenderer.java:258)
at de.smartics.maven.plugin.buildmetadata.BuildReportRenderer.renderSections(BuildReportRenderer.java:197)
at de.smartics.maven.plugin.buildmetadata.BuildReportRenderer.renderBody(BuildReportRenderer.java:170)
at de.smartics.maven.plugin.buildmetadata.BuildReportRenderer.renderReport(BuildReportRenderer.java:145)
at de.smartics.maven.plugin.buildmetadata.BuildReportMojo.executeReport(BuildReportMojo.java:138)
at org.apache.maven.reporting.AbstractMavenReport.generate(AbstractMavenReport.java:90)