fix: fix namespacing of array variables using unknowns

Author: AayushSabharwal

src/systems/abstractsystem.jl

@@ -1021,6 +1021,10 @@ function defaults(sys::AbstractSystem)
 end
 
 unknowns(sys::Union{AbstractSystem, Nothing}, v) = renamespace(sys, v)
+for vType in [Symbolics.Arr, Symbolics.Symbolic{<:AbstractArray}]
+    @eval unknowns(sys::AbstractSystem, v::$vType) = renamespace(sys, v)
+    @eval parameters(sys::AbstractSystem, v::$vType) = toparam(unknowns(sys, v))
+end
 parameters(sys::Union{AbstractSystem, Nothing}, v) = toparam(unknowns(sys, v))
 for f in [:unknowns, :parameters]
     @eval function $f(sys::AbstractSystem, vs::AbstractArray)

test/odesystem.jl

@@ -1159,3 +1159,9 @@ for sys in [sys1, sys2]
         @test variable_index(sys, x[i]) == variable_index(sys, x)[i]
     end
 end
+
+# Namespacing of array variables
+@variables x(t)[1:2]
+@named sys = ODESystem(Equation[], t)
+@test getname(unknowns(sys, x)) == :sys₊x
+@test size(unknowns(sys, x)) == size(x)