fix: fix initialization using u0map::Dict

Author: AayushSabharwal

src/systems/diffeqs/abstractodesystem.jl

@@ -874,8 +874,8 @@ function process_DEProblem(constructor, sys::AbstractODESystem, u0map, parammap;
             sys, t, u0map, parammap; guesses, warn_initialize_determined)
         initializeprobmap = getu(initializeprob, unknowns(sys))
 
-        zerovars = setdiff(unknowns(sys), keys(defaults(sys))) .=> 0.0
-        trueinit = identity.([zerovars; u0map])
+        zerovars = Dict(setdiff(unknowns(sys), keys(defaults(sys))) .=> 0.0)
+        trueinit = merge(zerovars, todict(u0map))
         u0map isa StaticArraysCore.StaticArray &&
             (trueinit = SVector{length(trueinit)}(trueinit))
     else
@@ -913,7 +913,6 @@ function process_DEProblem(constructor, sys::AbstractODESystem, u0map, parammap;
         du0 = nothing
         ddvs = nothing
     end
-
     check_eqs_u0(eqs, dvs, u0; kwargs...)
 
     f = constructor(sys, dvs, ps, u0; ddvs = ddvs, tgrad = tgrad, jac = jac,