revert: restore code fallbacks for config defaults

This reverts commit 153fc21. With no fallback in code, the deploy
crash-looped: Coolify keeps an entry for every variable compose.yml has
referenced, and empty entries appear to reach the containers as empty
values instead of the compose defaults.

internal/modules/sticker/addsticker_command_test.go

@@ -94,18 +94,17 @@ func TestAddSticker_NonOwnerWritesToConfiguredPack(t *testing.T) {
 	}
 }
 
-// There is no fallback pack: an unset STICKER_PACK_NAME must not write
-// anywhere.
-func TestAddSticker_RequiresPackName(t *testing.T) {
+func TestAddSticker_DefaultsToMiti99Pack(t *testing.T) {
 	rb := installAddSticker(t, "", "miti99bot")
 
 	rb.Bot.ProcessUpdate(context.Background(), stickerReply(999, "", "src", ""))
 
-	if _, ok := callTo(rb, "addStickerToSet"); ok {
-		t.Fatal("addStickerToSet called without a configured pack name")
+	call, ok := callTo(rb, "addStickerToSet")
+	if !ok {
+		t.Fatalf("no addStickerToSet call; got %+v", rb.Sent())
 	}
-	if _, ok := callTo(rb, "createNewStickerSet"); ok {
-		t.Fatal("createNewStickerSet called without a configured pack name")
+	if got := call.Form["name"]; got != "miti99_by_miti99bot" {
+		t.Errorf("name = %q, want the default pack", got)
 	}
 }
 

internal/modules/sticker/sticker_pack.go

@@ -17,15 +17,18 @@ import (
 )
 
 const (
-	// stickerPackNameEnv names the set /addsticker writes to; compose.yml
-	// supplies its default. The name must end in "_by_<bot_username>", the only thing that makes a set
+	// stickerPackNameEnv overrides which set /addsticker writes to. The name
+	// must end in "_by_<bot_username>", the only thing that makes a set
 	// bot-manageable; packTitle checks it before any upload. A set that does
 	// not exist yet is created by the first successful /addsticker.
 	stickerPackNameEnv = "STICKER_PACK_NAME"
 
+	// defaultStickerPackName is the shared pack used when the env is unset.
+	defaultStickerPackName = "miti99_by_miti99bot"
+
 	// stickerPackOwnerEnv reuses the bot-wide owner setting rather than
 	// introducing a second variable: AddStickerToSet needs the *set owner's*
-	// user ID, and the standard pack belongs to the bot owner. A pack
+	// user ID, and the default pack above belongs to the bot owner. A pack
 	// owned by any other account needs this env pointed at that account.
 	stickerPackOwnerEnv = "OWNER_ID"
 
@@ -75,10 +78,6 @@ type stickerPack struct {
 	OwnerID int64  // the account the set belongs to; AddStickerToSet demands it
 }
 
-// errNoPackName means STICKER_PACK_NAME is unset, so no sticker can be added.
-// Internal, not user-facing: nothing the caller does fixes a misconfiguration.
-var errNoPackName = errors.New("util: sticker pack name unset")
-
 // errNoPackOwner means the owner ID is unset, so no sticker can be added.
 // Internal, not user-facing: nothing the caller does fixes a misconfiguration.
 var errNoPackOwner = errors.New("util: sticker pack owner ID unset")
@@ -91,7 +90,7 @@ var errNoPackOwner = errors.New("util: sticker pack owner ID unset")
 func loadStickerPack() (stickerPack, error) {
 	name := strings.TrimSpace(os.Getenv(stickerPackNameEnv))
 	if name == "" {
-		return stickerPack{}, errNoPackName
+		name = defaultStickerPackName
 	}
 	ownerID, err := strconv.ParseInt(strings.TrimSpace(os.Getenv(stickerPackOwnerEnv)), 10, 64)
 	if err != nil || ownerID == 0 {

internal/modules/sticker/sticker_pack_test.go

@@ -106,36 +106,26 @@ func TestPackTitle_AtNameLengthCap(t *testing.T) {
 }
 
 func TestLoadStickerPack(t *testing.T) {
-	t.Run("reads the name and owner", func(t *testing.T) {
+	t.Run("defaults the name and requires an owner", func(t *testing.T) {
 		t.Setenv("OWNER_ID", "42")
-		t.Setenv("STICKER_PACK_NAME", "miti99_by_miti99bot")
+		t.Setenv("STICKER_PACK_NAME", "")
 		pack, err := loadStickerPack()
 		if err != nil {
 			t.Fatalf("loadStickerPack: %v", err)
 		}
-		if pack.Name != "miti99_by_miti99bot" {
-			t.Errorf("name = %q, want miti99_by_miti99bot", pack.Name)
+		if pack.Name != defaultStickerPackName {
+			t.Errorf("name = %q, want %q", pack.Name, defaultStickerPackName)
 		}
 		if pack.OwnerID != 42 {
 			t.Errorf("ownerID = %d, want 42", pack.OwnerID)
 		}
 	})
 
-	// No fallback name: an unset STICKER_PACK_NAME is a misconfiguration.
-	t.Run("requires a name", func(t *testing.T) {
-		t.Setenv("OWNER_ID", "42")
-		t.Setenv("STICKER_PACK_NAME", "")
-		if _, err := loadStickerPack(); !errors.Is(err, errNoPackName) {
-			t.Errorf("loadStickerPack() err = %v, want errNoPackName", err)
-		}
-	})
-
 	// A zero owner is the unset case, not a valid user: AddStickerToSet needs a
 	// real account, so it must fail here rather than at the API.
 	for _, owner := range []string{"", "0", "not-a-number"} {
 		t.Run("rejects owner "+owner, func(t *testing.T) {
 			t.Setenv("OWNER_ID", owner)
-			t.Setenv("STICKER_PACK_NAME", "miti99_by_miti99bot")
 			if _, err := loadStickerPack(); !errors.Is(err, errNoPackOwner) {
 				t.Errorf("loadStickerPack() err = %v, want errNoPackOwner", err)
 			}