Fatalw("...", err) logging pattern is invalid

[grantr]

#3866 added a bunch of logging statements that look like this:

logger.Fatalw("Version check failed: %v", err)

This is incorrect. Actually the err arg should be wrapped in a zap field:

logger.Fatalw("Version check failed: %v", zap.Error(err))

The sugared logger makes this extremely difficult to detect. One has to inspect the log message produced to see that it's wrong. This has come up before in knative/pkg#603 and #3345.

Eventing has the same issue since knative/eventing#1695.

<logging-rant> The non-sugared logger makes this a compile-time error instead of a runtime error at the cost of slightly more verbose (but type-safe and IMO easier to read) syntax. I much prefer it. </logging-rant>

In what area(s)?

/area monitoring

What version of Knative?

v0.9.0-123-gceaeb2350

Expected Behavior

When a fatal log occurs, it's logged successfully by zap.

Actual Behavior

Zap logs a message saying it's been called incorrectly:

{"level":"dpanic","ts":"2019-10-02T02:37:15.219Z","logger":"eventing-webhook","caller":"zap/sugar.go:210","msg":"Ignored key without a value.","commit":"a1a0981","knative.dev/controller":"eventing-webhook","ignored":"kubernetes version \"\" is not compatible, need at least \"v1.11.0\"","stacktrace":"main.main\n\t/home/prow/go/src/knative.dev/eventing/cmd/webhook/main.go:97\nruntime.main\n\t/usr/local/go/src/runtime/proc.go:200"}

(from knative/eventing#1991)

Steps to Reproduce the Problem

In this particular example, start any controller binary with the env var KUBERNETES_MIN_VERSION=1.15.0 or whatever version is greater than your cluster.