Velocity macro error in Syntax Guide when xwiki.section.depth=1

As reported by Kai Sen on the users list:
If one sets xwiki.section.depth=1 in the xwiki.cfg, then the XWiki.XWikiSyntax page does not show any content, but a velocity macro error; snippet from stack trace:

Caused by: java.lang.IndexOutOfBoundsException: Index: 1, Size: 1
	at java.util.ArrayList.rangeCheck(ArrayList.java:604)
	at java.util.ArrayList.get(ArrayList.java:382)
	at sun.reflect.GeneratedMethodAccessor162.invoke(Unknown Source)

Obviously filtering out the relevant sections from the subpages does not work when the xwiki.section.depth is changed