ModuleLoader: Do not cache Probes that throw errors
ModuleLoader: Do not cache Probes that throw errors

Doing so can hide errors, for instance when such a Probe is first run by
a non-required module instance.

Task-number: QBS-1074
Change-Id: Ibfbba029761b7d09d0a02eeaf5aa01f76c701574
Reviewed-by: Joerg Bornemann <47777b9406dbddd02a3fdca8341789a013805a11@qt.io>

qt-labs/qbs,qt-labs/qbs,qtproject/qt-labs-qbs,qtproject/qt-labs-qbs,qt-labs/qbs,qtproject/qt-labs-qbs,qt-labs/qbs,qt-labs/qbs,qtproject/qt-labs-qbs,qt-labs/qbs,qtproject/qt-labs-qbs,qtproject/qt-labs-qbs,qt-labs/qbs,qtproject/qt-labs-qbs