Bounds check hash, and fix some cases where states is a Vector{Any} instead of a Vector{BasicSymbolic{Real}}.

Author: chriselrod

src/systems/abstractsystem.jl

@@ -631,9 +631,17 @@ end
 function states(sys::AbstractSystem)
     sts = get_states(sys)
     systems = get_systems(sys)
-    unique(isempty(systems) ?
-           sts :
-           [sts; reduce(vcat, namespace_variables.(systems))])
+    nonunique_states = if isempty(systems)
+        sts
+    else
+        system_states = reduce(vcat, namespace_variables.(systems))
+        isempty(sts) ? system_states : [sts; system_states]
+    end
+    # `Vector{Any}` is incompatible with the `SymbolicIndexingInterface`, which uses
+    # `elsymtype = symbolic_type(eltype(_arg))` 
+    # which inappropriately returns `NotSymbolic()`
+    @assert typeof(nonunique_states) !== Vector{Any}
+    unique(nonunique_states)
 end
 
 function parameters(sys::AbstractSystem)

src/systems/connectors.jl

@@ -162,7 +162,14 @@ Base.isequal(l1::ConnectionElement, l2::ConnectionElement) = l1 == l2
 function Base.:(==)(l1::ConnectionElement, l2::ConnectionElement)
     nameof(l1.sys) == nameof(l2.sys) && isequal(l1.v, l2.v) && l1.isouter == l2.isouter
 end
-Base.hash(e::ConnectionElement, salt::UInt) = e.h ⊻ salt
+function Base.hash(e::ConnectionElement, salt::UInt)
+    @inbounds begin
+        @boundscheck begin
+            @assert e.h === _hash_impl(e.sys, e.v, e.isouter)
+        end
+    end
+    e.h ⊻ salt
+end
 namespaced_var(l::ConnectionElement) = states(l, l.v)
 states(l::ConnectionElement, v) = states(copy(l.sys), v)