core: (fixes 2815) Config::Connect should throw warnings
This patch logs unconditionally when a trace path doesn't exist.
We also provide FailSafe versions of Config::Connect and Config::ConnectWithoutContext. These should be used when you can't be sure that a trace path exists in the current model.
This resolves the warnings from AnimationInterface::ConnectCallbacks()
Credit to "InquisitivePenguin (GCI 2019) <>" for diagnosing this issue, opening the way to a solution.