Better error management.

* "Uncooperative cards" is now a warning.
* Cards and actions get "Then" invoked before the card processor considers erroring out.
* Terminal UI: Errors and warnings from actions are displayed during the response; they're not only added to the temporary messages now.

cardsim/messages.go

@@ -35,6 +35,19 @@ func Msgf(f string, args ...any) Message {
 	return stringMessage(fmt.Sprintf(f, args...))
 }
 
+// ErrorMessage returns a Message representing an Error.
+// This is preferred over Msgf for errors, since future versions of the library
+// may perform special message formatting for errors.
+func ErrorMessage(e error) Message {
+	if e == nil {
+		return nil
+	}
+	if IsSeriousError(e) {
+		return MultiMessage{MsgStr("SERIOUS ERROR:"), Msgf("%v", e)}
+	}
+	return MultiMessage{MsgStr("Warning:"), Msgf("%v", e)}
+}
+
 // A SpecialMessage is a specific, uniquely identifiable message.
 type SpecialMessage struct {
 	msg Message

cardsim/player.go

@@ -8,14 +8,14 @@ import (
 )
 
 var (
-	ErrUncooperativeCards = errors.New("a milion cards refused to join the hand")
 	ErrInvalidCard   = errors.New("invalid card specified")
 	ErrInvalidChoice = errors.New("invalid choice specified")
 	ErrNotUrgent     = errors.New("action not urgent when urgent card is available")
 	ErrNoActions     = errors.New("no actions remaining")
 	ErrNotDebugging  = errors.New("this is a debug-only feature and you're not in debug mode")
 
-	WarningStalemate = errors.New("no actions can be taken")
+	WarningStalemate         = &Warning{errors.New("no actions can be taken")}
+	WarningUncoperativeCards = &Warning{errors.New("a milion cards refused to join the hand")}
 )
 
 // Player stores all gameplay state for one player at a specific point in time.
@@ -272,9 +272,9 @@ func (p *Player[C]) StartNextTurn() error {
 }
 
 // Draw draws a card into the hand, informing the card that it has been drawn.
-// If more than a million cards refuse to enter the hand, this crashes with
-// ErrUncooperativeCards. If the deck does not have enough cards, this
-// returns WarningTooFewCards.
+// If more than a million cards refuse to enter the hand, this gives up and
+// returns WarningUncooperativeCards. If the deck does not have enough cards,
+// this returns WarningTooFewCards.
 func (p *Player[C]) Draw() error {
 	for attempts := 0; attempts < 1000000; attempts++ {
 		if p.Deck.Len() == 0 {
@@ -286,13 +286,13 @@ func (p *Player[C]) Draw() error {
 			return nil
 		}
 	}
-	return ErrUncooperativeCards
+	return WarningUncoperativeCards
 }
 
 // FillHand draws up to the hand limit, informing cards that they have been
-// drawn. If more than a million cards refuse to enter the hand, this crashes
-// with ErrUncooperativeCards. If the deck does not have enough cards, this
-// returns WarningTooFewCards.
+// drawn. If more than a million cards refuse to enter the hand, this gives up
+// and returns WarningUncooperativeCards. If the deck does not have enough
+// cards, this returns WarningTooFewCards.
 func (p *Player[C]) FillHand() error {
 	var lastErr error
 	for p.Deck.Len() > 0 && len(p.Hand) < p.HandLimit {
@@ -386,17 +386,14 @@ func (p *Player[C]) EnactCardUnchecked(cardIdx, choiceIdx int) (Message, error)
 
 	ret, err := options[choiceIdx].Enact(p)
 	errs.Add(err)
-	if IsSeriousError(err) {
-		p.State = GameCrashed
-		return ret, errs.Emit()
-	}
-
 	err = card.Then(p, options[choiceIdx])
 	errs.Add(err)
+
+	err = errs.Emit()
 	if IsSeriousError(err) {
 		p.State = GameCrashed
 	}
-	return ret, errs.Emit()
+	return ret, err
 }
 
 // EnactCard executes a card choice, removes it from the hand, and decrements
@@ -470,17 +467,13 @@ func (p *Player[C]) enactActionUnchecked(actionSource []Card[C], actionIdx, choi
 
 	ret, err := chosen.Enact(p)
 	errs.Add(err)
-	if IsSeriousError(err) {
-		p.State = GameCrashed
-		return ret, errs.Emit()
-	}
-
 	err = card.Then(p, chosen)
 	errs.Add(err)
-	if IsSeriousError(err) {
+	retErr := errs.Emit()
+	if IsSeriousError(retErr) {
 		p.State = GameCrashed
 	}
-	return ret, errs.Emit()
+	return ret, retErr
 }
 
 // EnactPermanentAction executes a permanently-available card and decrements
@@ -512,15 +505,11 @@ func (p *Player[C]) ReportError(e error) {
 	if e == nil || p.DebugLevel < -1 {
 		return
 	}
-	if p.DebugLevel < 0 && !IsSeriousError(e) {
-		return
-	}
-	p.ChapterBreak()
-	severity := "[Warning]"
+	minLvl := NotDebugging
 	if IsSeriousError(e) {
-		severity = "[ERROR]"
+		minLvl = HideWarnings
 	}
-	p.TemporaryMessages = append(p.TemporaryMessages, Msgf("%s: %v", severity, e))
+	p.Debug(minLvl, ErrorMessage(e))
 }
 
 // CanAct returns whether the player has actions theoretically available.
@@ -534,6 +523,7 @@ func (p *Player[C]) Debug(minLevel int, msg Message) {
 	if p.DebugLevel < minLevel || msg == nil {
 		return
 	}
+	p.ChapterBreak()
 	p.TemporaryMessages = append(p.TemporaryMessages, msg)
 }
 

cardsim/terminalui.go

@@ -46,6 +46,10 @@ func RunSimpleTerminalUI[C StatsCollection](p *Player[C]) error {
 				}
 				continue
 			}
+			if err != nil {
+				display(ErrorMessage(err))
+				display(MsgStr(""))
+			}
 			display(msg)
 			wait()
 		}