Fix dispatch issues with CFL callback

examples/heat_vgfc_seb_samoylov_custom.jl

@@ -50,6 +50,7 @@ p.soil.n .= 2.0
 p.soil.Tₘ .= 273.15 # K
 # CryoGrid front-end for ODEProblem
 prob = CryoGridProblem(model,tspan,p)
+# OPTIONAL: solve for short time period to 
 # solve with forward Euler (w/ CFL) and construct CryoGridOutput from solution
 out = @time solve(prob, Euler(), dt=2*60.0, callback=CFLStepLimiter(model), saveat=24*3600.0, progress=true) |> CryoGridOutput;
 # Plot it!

src/Callbacks/Callbacks.jl

@@ -4,6 +4,7 @@ import CryoGrid
 
 using CryoGrid.Numerics
 using CryoGrid.Setup: CryoGridSetup, HeatOnlySetup, getvar
+using CryoGrid.Utils
 
 using DiffEqCallbacks
 

src/Callbacks/courant_step.jl

@@ -2,7 +2,7 @@ struct CFLHeatState{A}
     Δt::A
     default_dt::Float64
 end
-function (fn::CryoGridCallbackFunction{CFLHeatState{<:AbstractArray}})(u,p,t)
+function (fn::CryoGridCallbackFunction{<:CFLHeatState{<:AbstractArray}})(u,p,t)
     let Δt = fn.state.Δt,
         Δx = Δ(fn.setup.grid),
         Ceff = getvar(:Ceff, fn.setup, u), # apparent heat capacity
@@ -12,7 +12,7 @@ function (fn::CryoGridCallbackFunction{CFLHeatState{<:AbstractArray}})(u,p,t)
         IfElse.ifelse(isfinite(Δt_min), Δt_min, fn.default_dt)
     end
 end
-function (fn::CryoGridCallbackFunction{CFLHeatState{Nothing}})(u,p,t)
+function (fn::CryoGridCallbackFunction{<:CFLHeatState{Nothing}})(u,p,t)
     let Δx = Δ(fn.setup.grid),
         Ceff = getvar(:Ceff, fn.setup, u), # apparent heat capacity
         kc = getvar(:kc, fn.setup, u); # thermal cond. at grid centers