Fix npe in reconciler

[mjudeikis]

Description of your changes

The problem is that when r.external.Connect(externalCtx, managed) fails at line 1086, the code returns early at line 1102, but the defer function at line 1105 still executes. However, since the Connect call failed, the external variable was ever properly assigned a valid value, so it's nil.

When the defer function tries to call external.Disconnect(ctx) at line 1111, it's trying to call a method on a nil pointer, causing the panic.

k8s.io/apimachinery/pkg/util/runtime.logPanic({0x1395160, 0x259ae40})
        k8s.io/apimachinery@v0.30.0/pkg/util/runtime/runtime.go:75 +0x7c
sigs.k8s.io/controller-runtime/pkg/internal/controller.(*Controller).Reconcile.func1()
        sigs.k8s.io/controller-runtime@v0.18.2/pkg/internal/controller/controller.go:103 +0xa4
panic({0x1395160?, 0x259ae40?})
        runtime/panic.go:770 +0x124
github.com/crossplane/crossplane-runtime/pkg/reconciler/managed.ExternalClientFns.Disconnect(...)
        github.com/crossplane/crossplane-runtime@v1.17.0/pkg/reconciler/managed/reconciler.go:387
github.com/crossplane/crossplane-runtime/pkg/reconciler/managed.(*Reconciler).Reconcile.func2()
        github.com/crossplane/crossplane-runtime@v1.17.0/pkg/reconciler/managed/reconciler.go:967 +0x1e8
github.com/crossplane/crossplane-runtime/pkg/reconciler/managed.(*Reconciler).Reconcile(0x400033f560, {0x18964c8, 0x40007c5c20}, {{{0x0, 0x0}, {0x40006fa940, 0x3d}}})
        github.com/crossplane/crossplane-runtime@v1.17.0/pkg/reconciler/managed/reconciler.go:1253 +0x758c
github.com/crossplane/crossplane-runtime/pkg/ratelimiter.(*Reconciler).Reconcile(0x400016a690, {0x18964c8, 0x40007c5c20}, {{{0x0?, 0x400015dca8?}, {0x40006fa940?, 0x400015dd08?}}})
        github.com/crossplane/crossplane-runtime@v1.17.0/pkg/ratelimiter/reconciler.go:54 +0x124
sigs.k8s.io/controller-runtime/pkg/internal/controller.(*Controller).Reconcile(0x189ab10?, {0x18964c8?, 0x40007c5c20?}, {{{0x0?, 0xb?}, {0x40006fa940?, 0x0?}}})
        sigs.k8s.io/controller-runtime@v0.18.2/pkg/internal/controller/controller.go:114 +0x8c
sigs.k8s.io/controller-runtime/pkg/internal/controller.(*Controller).reconcileHandler(0x400014e4d0, {0x1896500, 0x4000149d10}, {0x141fb40, 0x40000b2140})
        sigs.k8s.io/controller-runtime@v0.18.2/pkg/internal/controller/controller.go:311 +0x2dc
sigs.k8s.io/controller-runtime/pkg/internal/controller.(*Controller).processNextWorkItem(0x400014e4d0, {0x1896500, 0x4000149d10})
        sigs.k8s.io/controller-runtime@v0.18.2/pkg/internal/controller/controller.go:261 +0x16c
sigs.k8s.io/controller-runtime/pkg/internal/controller.(*Controller).Start.func2.2()
        sigs.k8s.io/controller-runtime@v0.18.2/pkg/internal/controller/controller.go:222 +0x74
created by sigs.k8s.io/controller-runtime/pkg/internal/controller.(*Controller).Start.func2 in goroutine 99
        sigs.k8s.io/controller-runtime@v0.18.2/pkg/internal/controller/controller.go:218 +0x3bc

Fixes #

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[jbw976]

This looks reasonable, thank you for taking the time to make this change @mjudeikis and to explain how it is caused too! 🙇‍♂️

[jbw976]

Approved CI workflows to run just now...