Instead of just asserting when an invalid property is requested, use the property validity test to do some error checking.  If an invalid property is requested, a loud error message is printed, and *then* the assertion failure occurs.
Instead of just asserting when an invalid property is requested, use the
property validity test to do some error checking.  If an invalid property
is requested, a loud error message is printed, and *then* the assertion
failure occurs.


git-svn-id: 769d22dfa2d22aad706b9a451492fb87c0735f19@13307 08b38cba-cd3b-11de-854e-f91c5b6e4272

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