Fix: reinit! error when using AbsTerminationMode

Author: AJ0070

lib/NonlinearSolveBase/src/termination_conditions.jl

@@ -98,10 +98,12 @@ function SciMLBase.reinit!(
     length(saved_value_prototype) != 0 && (cache.saved_values = saved_value_prototype)
 
     mode = cache.mode
-    if u isa Number || !ArrayInterface.can_setindex(u)
-        cache.u = u
-    else
-        cache.u .= u
+    if cache.u !== nothing
+        if u isa Number || !ArrayInterface.can_setindex(u)
+            cache.u = u
+        else
+            cache.u .= u
+        end
     end
     cache.retcode = ReturnCode.Default
 

lib/NonlinearSolveBase/test/runtests.jl

@@ -33,4 +33,20 @@ using InteractiveUtils, Test
 
         @test NonlinearSolveBase.Utils.faster_vcat(b, d) == vcat(sparse(b), d)
     end
+
+    @testset "Termination Conditions" begin
+        using NonlinearSolveBase, SciMLBase
+        @testset "reinit! with AbsTerminationMode" begin
+            mode = NonlinearSolveBase.AbsTerminationMode()
+            u_unaliased = nothing
+            T = Float64
+            cache = NonlinearSolveBase.NonlinearTerminationModeCache(
+                u_unaliased, SciMLBase.ReturnCode.Default, 1e-8, 1e-8, Inf, mode,
+                nothing, nothing, 0, nothing, nothing, nothing, nothing, nothing, false
+            )
+            du = [1.0, 1.0]
+            u = [1.1, 1.1]
+            @test_nowarn SciMLBase.reinit!(cache, du, u)
+        end
+    end
 end