refactor: default to use_union = false for ODEProblems

Author: AayushSabharwal

src/systems/diffeqs/abstractodesystem.jl

@@ -772,7 +772,7 @@ function process_DEProblem(constructor, sys::AbstractODESystem, u0map, parammap;
         linenumbers = true, parallel = SerialForm(),
         eval_expression = false,
         eval_module = @__MODULE__,
-        use_union = true,
+        use_union = false,
         tofloat = true,
         symbolic_u0 = false,
         u0_constructor = identity,

src/systems/jumps/jumpsystem.jl

@@ -446,7 +446,7 @@ oprob = ODEProblem(complete(js), u₀map, tspan, parammap)
 """
 function DiffEqBase.ODEProblem(sys::JumpSystem, u0map, tspan::Union{Tuple, Nothing},
         parammap = DiffEqBase.NullParameters();
-        use_union = true,
+        use_union = false,
         eval_expression = false,
         eval_module = @__MODULE__,
         kwargs...)