fix for systems with no dynamics
fix for systems with no dynamics

paulstapor/AMICI,paulstapor/AMICI,FFroehlich/AMICI,paulstapor/AMICI,FFroehlich/AMICI,AMICI-developer/AMICI,AMICI-developer/AMICI,AMICI-developer/AMICI,AMICI-developer/AMICI,FFroehlich/AMICI,paulstapor/AMICI,FFroehlich/AMICI