fix: simplify if not simplified

Author: vyudu

src/linearization.jl

@@ -46,7 +46,7 @@ function linearization_function(sys::AbstractSystem, inputs = unbound_inputs(sys
         warn_empty_op = true,
         kwargs...)
     if !iscomplete(sys)
-        error("A completed `ODESystem` is required. Call `complete` or `mtkbuild` on the system before creating the linearization.")
+        sys = mtkbuild(sys; inputs, outputs)
     end
     op = Dict(op)
     if isempty(op) && warn_empty_op

test/downstream/linearize.jl

@@ -268,7 +268,6 @@ closed_loop = ODESystem(connections, t, systems = [model, pid, filt, sensor, r,
         filt.x => 0.0,
         filt.xd => 0.0
     ])
-closed_loop = mtkbuild(closed_loop)
 
 @test_nowarn linearize(closed_loop, :r, :y; warn_empty_op = false)