Fix type instability

Author: hersle

src/remake.jl

@@ -229,7 +229,7 @@ function remake(prob::ODEProblem; f = missing,
 
     iip = isinplace(prob)
 
-    if build_initializeprob == Val{true} || build_initializeprob == true
+    if build_initializeprob isa Val{true} || build_initializeprob == true
         if f !== missing && has_initialization_data(f)
             initialization_data = remake_initialization_data(
                 prob.f.sys, f, u0, tspan[1], p, newu0, newp)

test/downstream/solution_interface.jl

@@ -349,3 +349,10 @@ end
     sol = solve(prob)
     @test sol(0.6, idxs = y) ≈ 2.0
 end
+
+@testset "Type stability of MTK workflow" begin
+    @variables x(t)
+    @mtkbuild sys = ODESystem([D(x) ~ 0.0], t; defaults = [x => 0.0])
+    prob = ODEProblem(sys, [], (0.0, 1.0))
+    @test_nowarn @inferred solve(prob, Tsit5())
+end