buildReducedModel and addJointFrames

[abussy-aldebaran]

Bug description

If not all joints are also added as frames with addJointFrame, buildReducedModel fails.

Expected behavior

buildReducedModel does not fails, or assert that joint frames are missing (plus a mention in the documentation).

Reproduction steps

Code

I added tests in my fork : abussy-aldebaran@e7d6630

test_buildReducedModel_with_joint_frames passes.
test_buildReducedModel_without_any_joint_frames crashes (memory access violation)
test_buildReducedModel_without_joint_frames raises an assert : "Frame index out of bound"

Discussion

Reading the code of buildReducedModel, I guess that it is expected that all joints have an attached frame.
More generally, is using addJointFrame mandatory, recommended, or good practice ? Why isn't it done within addJoint then ?

Regarding buildReducedModel, if the solution is to add an assert + doc, I can submit a PR.