Minor fix

Author: YingboMa

src/systems/diffeqs/odesystem.jl

@@ -173,7 +173,7 @@ function ODESystem(eqs, iv=nothing; kwargs...)
     iv === nothing && throw(ArgumentError("Please pass in independent variables."))
     compressed_eqs = Equation[] # equations that need to be expanded later, like `connect(a, b)`
     for eq in eqs
-        eq.lhs isa Symbolic || (push!(compressed_eqs, eq); continue)
+        eq.lhs isa Union{Symbolic,Number} || (push!(compressed_eqs, eq); continue)
         collect_vars!(allstates, ps, eq.lhs, iv)
         collect_vars!(allstates, ps, eq.rhs, iv)
         if isdiffeq(eq)

src/utils.jl

@@ -359,7 +359,7 @@ $(SIGNATURES)
 
 find duplicates in an iterable object.
 """
-function find_duplicates(xs, ::Val{Ret}) where Ret
+function find_duplicates(xs, ::Val{Ret}=Val(false)) where Ret
     appeared = Set()
     duplicates = Set()
     for x in xs
@@ -369,5 +369,5 @@ function find_duplicates(xs, ::Val{Ret}) where Ret
             push!(appeared, x)
         end
     end
-    return Ret ? duplicates : (appeared, duplicates)
+    return Ret ? (appeared, duplicates) : duplicates
 end

test/discretesystem.jl

@@ -112,13 +112,3 @@ linearized_eqs = [
     y(t - 2.0) ~ y(t)
 ]
 @test all(eqs2 .== linearized_eqs)
-
-# Test connector_type
-@connector function DiscreteComponent(;name)
-    @variables v(t) i(t)
-    DiscreteSystem(Equation[], t, [v, i], [], name=name, defaults=Dict(v=>1.0, i=>1.0))
-end
-
-@named d1 = DiscreteComponent()
-
-@test ModelingToolkit.get_connector_type(d1) == DiscreteComponent