NullPointerException when the content does not contain a table

Steps to reproduce:

Insert the following macro call in a page's wiki syntax:

{{livedata-inline-table}}
{{/livedata-inline-table}} 

Then, click save and view.

Expected result:

• A message explains that the macro content should contain a table.

Current result:

• An error message is displayed: 

  Failed to execute the [livedata-inline-table] macro. Cause: [Cannot invoke "org.xwiki.rendering.block.TableBlock.getChildren()" because "table" is null]. Click on this message for details.