make retrieveCardDefinition errors recoverable

This is needed ro test if a user provided path is an actual card and not
crash the program if not.

1 files changed, 25 insertions, 9 deletions

diff --git a/go/game/card.go b/go/game/card.go
index 90dd8f2b..70c591b7 100644
--- a/go/game/card.go
+++ b/go/game/card.go
@@ -162,24 +162,28 @@ type Card struct {
 
 var cardDefinitions = map[string]map[string][]byte{}
 
-func getCardDefinition(set, cardName string) []byte {
+func getCardDefinition(set, cardName string) ([]byte, error) {
 	cardDefinition, found := cardDefinitions[set][cardName]
 	if !found {
-		cardDefinition = retrieveCardDefinition(path.Join(set, cardName))
+		var err error
+		cardDefinition, err = retrieveCardDefinition(path.Join(set, cardName))
+		if err != nil {
+			return nil, err
+		}
 		if cardDefinitions[set] == nil {
 			cardDefinitions[set] = map[string][]byte{}
 		}
 		cardDefinitions[set][cardName] = cardDefinition
 	}
-	return cardDefinition
+	return cardDefinition, nil
 }
 
-func retrieveCardDefinition(cardPath string) []byte {
+func retrieveCardDefinition(cardPath string) ([]byte, error) {
 	url := PROTOCOL + path.Join(BASE_URL, CARD_DATA_URL, cardPath+".yml")
 	log.Printf("loading %s\n", url)
 	resp, err := http.Get(url)
 	if err != nil {
-		log.Fatal(err)
+		return nil, err
 	}
 
 	defer resp.Body.Close()
@@ -187,7 +191,7 @@ func retrieveCardDefinition(cardPath string) []byte {
 	if err != nil {
 		log.Fatal(err)
 	}
-	return data
+	return data, nil
 }
 
 func (card *Card) parseDefinition(definition []byte) {
@@ -323,11 +327,23 @@ func (card *Card) getAI() string {
 	return strings.Split(aiDesc[0], " ")[0]
 }
 
+// Create a new card from the path.
+// Panic if the path is not valid.
 func NewCard(cardPath string) *Card {
+	card, err := NewCardSafe(cardPath)
+	if err != nil {
+		log.Fatal(err)
+	}
+	return card
+}
+
+// Safely create a new card from the path.
+// Return an error if the path is invalid.
+func NewCardSafe(cardPath string) (*Card, error) {
 	cardName := path.Base(cardPath)
 	set := path.Dir(cardPath)
 
-	cardDefinition := getCardDefinition(set, cardName)
+	cardDefinition, err := getCardDefinition(set, cardName)
 
 	c := Card{
 		Name:      "",
@@ -335,10 +351,10 @@ func NewCard(cardPath string) *Card {
 		Type:      undefinedCardType,
 		BuyCosts:  nil,
 		PlayCosts: nil,
-		Values:    map[string]interface{}{},
+		Values:    map[string]any{},
 	}
 	c.parseDefinition(cardDefinition)
-	return &c
+	return &c, err
 }
 
 func (c *Card) Path() string {