For instance, it happens from time to time that users try to build a Qt project with their cpp profile, so most Qt properties are undefined. For instance:

$ qbs -f ../qtcreator-master profile:gcc
/home/christian/dev/qtcreator-master/src/plugins/help/help.qbs:30 TypeError: Result of expression 'version' [undefined] is not an object.

There is no such expression in line 30 of the help.qbs file. However, there is such an expression on line 30 of Qt/core.qbs, which leads me to believe that qbs just uses the wrong file name when constructing the error location.