Update build_observed_function as well

Author: YingboMa

src/structural_transformation/codegen.jl

@@ -386,7 +386,7 @@ function build_observed_function(
     if (isscalar = !(ts isa AbstractVector))
         ts = [ts]
     end
-    ts = Symbolics.scalarize.(value.(ts))
+    ts = unwrap.(Symbolics.scalarize(ts))
 
     vars = Set()
     sys = state.sys