fmsg: implement suspend in writer

This removes the requirement to call fmsg.Exit on every exit path, and enables direct use of the "log" package. However, fmsg.BeforeExit is still encouraged when possible to catch exit on suspended output.

Signed-off-by: Ophestra <cat@gensokyo.uk>

error.go

@@ -2,6 +2,7 @@ package main
 
 import (
 	"errors"
+	"log"
 
 	"git.gensokyo.uk/security/fortify/internal/app"
 	"git.gensokyo.uk/security/fortify/internal/fmsg"
@@ -10,13 +11,13 @@ import (
 func logWaitError(err error) {
 	var e *fmsg.BaseError
 	if !fmsg.AsBaseError(err, &e) {
-		fmsg.Println("wait failed:", err)
+		log.Println("wait failed:", err)
 	} else {
 		// Wait only returns either *app.ProcessError or *app.StateStoreError wrapped in a *app.BaseError
 		var se *app.StateStoreError
 		if !errors.As(err, &se) {
 			// does not need special handling
-			fmsg.Print(e.Message())
+			log.Print(e.Message())
 		} else {
 			// inner error are either unwrapped store errors
 			// or joined errors returned by *appSealTx revert
@@ -24,7 +25,7 @@ func logWaitError(err error) {
 			var ej app.RevertCompoundError
 			if !errors.As(se.InnerErr, &ej) {
 				// does not require special handling
-				fmsg.Print(e.Message())
+				log.Print(e.Message())
 			} else {
 				errs := ej.Unwrap()
 
@@ -33,10 +34,10 @@ func logWaitError(err error) {
 					var eb *fmsg.BaseError
 					if !errors.As(ei, &eb) {
 						// unreachable
-						fmsg.Println("invalid error type returned by revert:", ei)
+						log.Println("invalid error type returned by revert:", ei)
 					} else {
 						// print inner *app.BaseError message
-						fmsg.Print(eb.Message())
+						log.Print(eb.Message())
 					}
 				}
 			}
@@ -48,8 +49,8 @@ func logBaseError(err error, message string) {
 	var e *fmsg.BaseError
 
 	if fmsg.AsBaseError(err, &e) {
-		fmsg.Print(e.Message())
+		log.Print(e.Message())
 	} else {
-		fmsg.Println(message, err)
+		log.Println(message, err)
 	}
 }