Initialize DISCO checkpoint from the time value (#4069)

Co-authored-by: ChrisRackauckas-Claude <accounts@chrisrackauckas.com>

Author: ChrisRackauckas-Claude

lib/OrdinaryDiffEqCore/src/solve.jl

@@ -760,7 +760,7 @@ Base.@constprop :aggressive function _ode_init(
     controller_cache = setup_controller_cache(_alg, cache, controller, EEstT, disco_probs)
 
     is_disco_step = false
-    disco_checkpoint = zero(tType)
+    disco_checkpoint = zero(t)
     # Seed the initial EEst on the controller cache (was previously
     # `integrator.EEst = oneunit(EEstT)`).
     set_EEst!(controller_cache, EEst)

test/Downstream/dynamicquantities_measurements.jl

@@ -10,7 +10,11 @@ using Test
     f(u, p, t) = u / (1u"s")
     prob = ODEProblem(f, u0, tspan)
 
-    sol = solve(prob, Tsit5(); abstol = 1.0e-9, reltol = 1.0e-9)
+    integrator = init(prob, Tsit5(); abstol = 1.0e-9, reltol = 1.0e-9)
+    @test integrator.disco_checkpoint == zero(first(tspan))
+    @test typeof(integrator.disco_checkpoint) == typeof(first(tspan))
+
+    sol = solve!(integrator)
 
     @test sol.u[end] isa typeof(u0)
     @test eltype(sol.u) == typeof(u0)