fix: handle parameter dependencies with constant RHS

src/systems/diffeqs/odesystem.jl

@@ -335,11 +335,7 @@ function ODESystem(eqs, iv; kwargs...)
         end
     end
     for eq in get(kwargs, :parameter_dependencies, Equation[])
-        if eq isa Pair
-            collect_vars!(allunknowns, ps, eq, iv)
-        else
-            collect_vars!(allunknowns, ps, eq, iv)
-        end
+        collect_vars!(allunknowns, ps, eq, iv)
     end
     for ssys in get(kwargs, :systems, ODESystem[])
         collect_scoped_vars!(allunknowns, ps, ssys, iv)

src/utils.jl

@@ -252,6 +252,7 @@ end
 
 function collect_defaults!(defs, vars)
     for v in vars
+        symbolic_type(v) == NotSymbolic() && continue
         if haskey(defs, v) || !hasdefault(unwrap(v)) || (def = getdefault(v)) === nothing
             continue
         end
@@ -262,6 +263,7 @@ end
 
 function collect_var_to_name!(vars, xs)
     for x in xs
+        symbolic_type(x) == NotSymbolic() && continue
         x = unwrap(x)
         if hasmetadata(x, Symbolics.GetindexParent)
             xarr = getmetadata(x, Symbolics.GetindexParent)

test/odesystem.jl

@@ -1442,3 +1442,8 @@ end
         end
     end
 end
+
+@testset "Parameter dependencies with constant RHS" begin
+    @parameters p
+    @test_nowarn ODESystem(Equation[], t; parameter_dependencies = [p ~ 1.0], name = :a)
+end