juju-engine-report triggering panic

[John A Meinel]

On PS5-beta we are seeing:
panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x78 pc=0x20b1e2f]

goroutine 20111973 [running]:
github.com/juju/juju/worker/uniter.(*Uniter).Report(0xc041215b00)
 /home/jenkins/workspace/BuildJuju-amd64/_build/src/github.com/juju/juju/worker/uniter/uniter.go:986 +0xaf
github.com/juju/worker/v3/dependency.(*Engine).manifoldsReport(0xc018decd80)
 /home/jenkins/workspace/BuildJuju-amd64/_build/src/github.com/juju/juju/vendor/github.com/juju/worker/v3/dependency/engine.go:314 +0x45c
github.com/juju/worker/v3/dependency.(*Engine).liveReport(0xc018decd80)
 /home/jenkins/workspace/BuildJuju-amd64/_build/src/github.com/juju/juju/vendor/github.com/juju/worker/v3/dependency/engine.go:285 +0xfd
github.com/juju/worker/v3/dependency.(*Engine).loop(0xc018decd80)
 /home/jenkins/workspace/BuildJuju-amd64/_build/src/github.com/juju/juju/vendor/github.com/juju/worker/v3/dependency/engine.go:213 +0x26e
gopkg.in/tomb%2ev2.(*Tomb).run(0xc018decdf0, 0xc00dea6e20)
 /home/jenkins/workspace/BuildJuju-amd64/_build/src/github.com/juju/juju/vendor/gopkg.in/tomb.v2/tomb.go:163 +0x36
created by gopkg.in/tomb%2ev2.(*Tomb).Go
 /home/jenkins/workspace/BuildJuju-amd64/_build/src/github.com/juju/juju/vendor/gopkg.in/tomb.v2/tomb.go:159 +0xf3

Everything in engine report should be extra careful since it is the tool to introspect when things are going wrong. This panic is actually causing the entire controller to restart.