[errors] Greatly simplify common/errors package.

logdog/client/cli/subcommandCat.go

Index: logdog/client/cli/subcommandCat.go
diff --git a/logdog/client/cli/subcommandCat.go b/logdog/client/cli/subcommandCat.go
index a770eaef718bcd0e6e5038f0d67968cb625583b2..4f4aad2880562cadf6d17cc7fae571a82501ad52 100644
--- a/logdog/client/cli/subcommandCat.go
+++ b/logdog/client/cli/subcommandCat.go
@@ -121,8 +121,7 @@ func (cmd *catCommandRun) Run(scApp subcommands.Application, args []string, _ su
 		}
 
 		if addr.Host, err = a.resolveHost(""); err != nil {
-			err = errors.Annotate(err).Reason("failed to resolve host: %(host)q").
-				D("host", addr.Host).Err()
+			err = errors.Annotate(err, "failed to resolve host: %q", addr.Host).Err()
 			errors.Log(a, err)
 			return 1
 		}
@@ -143,8 +142,7 @@ func (cmd *catCommandRun) Run(scApp subcommands.Application, args []string, _ su
 
 		var err error
 		if coords[addr.Host], err = a.coordinatorClient(addr.Host); err != nil {
-			err = errors.Annotate(err).Reason("failed to create Coordinator client for %(host)q").
-				D("host", addr.Host).Err()
+			err = errors.Annotate(err, "failed to create Coordinator client for %q", addr.Host).Err()
 
 			errors.Log(a, err)
 			return 1