New failure to simplify algebraic equations

[baggepinnen]

A somewhat recent change broke simplification of an example in the JuliaSimControl docs. The error is

ExtraEquationsSystemException: The system is unbalanced. There are 41 highest order derivative variables and 44 equations.

and the 4 extra equations reported are all algebraic:

 0 ~ model₊inertia2₊phi(t) - model₊damper₊phi_rel(t) - model₊inertia1₊phi(t)
 0 ~ -state_feedback₊output₊u(t) - 6.366552244884042(state_feedback₊input₊u(t))[2]
 0 ~ -state_feedback₊output₊u(t) - 12.386063825133666(state_feedback₊input₊u(t))[3]
 0 ~ -state_feedback₊output₊u(t) - 1.756071798599596(state_feedback₊input₊u(t))[4]

The error can be reproduced by running the first two code cells in the tutorial, the example hasn't changed (except for the now required @named torque = Torque(use_support=false))

[baggepinnen]

Fixed by SciML/ModelingToolkitStandardLibrary.jl#212