treewide: add missing error handling

Change-Id: I55ccf3ff490b58f6af93e665c668428acddc8d65
Reviewed-on: https://review.monogon.dev/c/monogon/+/3019
Vouch-Run-CI: Tim Windelschmidt <tim@monogon.tech>
Tested-by: Jenkins CI
Reviewed-by: Serge Bazanski <serge@monogon.tech>
diff --git a/metropolis/pkg/logtree/unraw/unraw_test.go b/metropolis/pkg/logtree/unraw/unraw_test.go
index 5526feb..71c88fd 100644
--- a/metropolis/pkg/logtree/unraw/unraw_test.go
+++ b/metropolis/pkg/logtree/unraw/unraw_test.go
@@ -112,6 +112,7 @@
 		close(started)
 		return r(ctx)
 	})
+	defer stop()
 
 	<-started