Fix issue with computing derivative term beyond specified order

When numba is deactivated, the test fails due to the attempt to compute the derivative of monomial beyond the specified order. When numba is activated, there is no strict array bound checking so no error was raised (although the results remain correct).

Furthermore, a test from JIT-compiled combinations are removed because the exception is only raised when numba is activated.

This MR should resolve Issue #146 (closed).