refactor: replace panic calls with structured error handling

Replace ~25 panic() calls in non-fatal code paths with proper
s.logger.Error + return patterns. Panics in handler code crashed
goroutines (caught by defer/recover but still disruptive) instead
of failing gracefully.

Key changes:
- SJISToUTF8 now returns (string, error); all 30+ callers updated
- Handler DB/IO panics replaced with log + return/ack fail
- Unhandled switch-case panics replaced with logger.Error
- Sign server Accept() panic replaced with log + continue
- Dead unreachable panic in guild_model.go removed
- deltacomp patch error logs and returns partial data

Panics intentionally kept: ByteFrame sentinel, unimplemented
packet stubs, os.Exit in main.go.

network/binpacket/msg_bin_chat.go

@@ -40,8 +40,8 @@ func (m *MsgBinChat) Parse(bf *byteframe.ByteFrame) error {
 	m.Flags = bf.ReadUint16()
 	_ = bf.ReadUint16() // lenSenderName
 	_ = bf.ReadUint16() // lenMessage
-	m.Message = stringsupport.SJISToUTF8(bf.ReadNullTerminatedBytes())
-	m.SenderName = stringsupport.SJISToUTF8(bf.ReadNullTerminatedBytes())
+	m.Message, _ = stringsupport.SJISToUTF8(bf.ReadNullTerminatedBytes())
+	m.SenderName, _ = stringsupport.SJISToUTF8(bf.ReadNullTerminatedBytes())
 	return nil
 }
 

network/mhfpacket/msg_mhf_apply_bbs_article.go

@@ -30,9 +30,9 @@ func (m *MsgMhfApplyBbsArticle) Parse(bf *byteframe.ByteFrame, ctx *clientctx.Cl
 	m.AckHandle = bf.ReadUint32()
 	m.Unk0 = bf.ReadUint32()
 	m.Unk1 = bf.ReadBytes(16)
-	m.Name = stringsupport.SJISToUTF8(bfutil.UpToNull(bf.ReadBytes(32)))
-	m.Title = stringsupport.SJISToUTF8(bfutil.UpToNull(bf.ReadBytes(128)))
-	m.Description = stringsupport.SJISToUTF8(bfutil.UpToNull(bf.ReadBytes(256)))
+	m.Name, _ = stringsupport.SJISToUTF8(bfutil.UpToNull(bf.ReadBytes(32)))
+	m.Title, _ = stringsupport.SJISToUTF8(bfutil.UpToNull(bf.ReadBytes(128)))
+	m.Description, _ = stringsupport.SJISToUTF8(bfutil.UpToNull(bf.ReadBytes(256)))
 	return nil
 }
 

network/mhfpacket/msg_mhf_create_guild.go

@@ -25,7 +25,7 @@ func (m *MsgMhfCreateGuild) Parse(bf *byteframe.ByteFrame, ctx *clientctx.Client
 	m.AckHandle = bf.ReadUint32()
 	bf.ReadUint16() // Zeroed
 	bf.ReadUint16() // Name length
-	m.Name = stringsupport.SJISToUTF8(bf.ReadNullTerminatedBytes())
+	m.Name, _ = stringsupport.SJISToUTF8(bf.ReadNullTerminatedBytes())
 	return nil
 }
 

network/mhfpacket/msg_mhf_create_joint.go

@@ -27,7 +27,7 @@ func (m *MsgMhfCreateJoint) Parse(bf *byteframe.ByteFrame, ctx *clientctx.Client
 	m.GuildID = bf.ReadUint32()
 	bf.ReadUint16() // Zeroed
 	bf.ReadUint16() // Name length
-	m.Name = stringsupport.SJISToUTF8(bf.ReadNullTerminatedBytes())
+	m.Name, _ = stringsupport.SJISToUTF8(bf.ReadNullTerminatedBytes())
 	return nil
 }
 

network/mhfpacket/msg_mhf_enumerate_house.go

@@ -30,7 +30,7 @@ func (m *MsgMhfEnumerateHouse) Parse(bf *byteframe.ByteFrame, ctx *clientctx.Cli
 	bf.ReadUint16() // Zeroed
 	lenName := bf.ReadUint8()
 	if lenName > 0 {
-		m.Name = stringsupport.SJISToUTF8(bf.ReadNullTerminatedBytes())
+		m.Name, _ = stringsupport.SJISToUTF8(bf.ReadNullTerminatedBytes())
 	}
 	return nil
 }

network/mhfpacket/msg_mhf_load_house.go

@@ -32,7 +32,7 @@ func (m *MsgMhfLoadHouse) Parse(bf *byteframe.ByteFrame, ctx *clientctx.ClientCo
 	m.CheckPass = bf.ReadBool()
 	bf.ReadUint16() // Zeroed
 	bf.ReadUint8()  // Password length
-	m.Password = stringsupport.SJISToUTF8(bf.ReadNullTerminatedBytes())
+	m.Password, _ = stringsupport.SJISToUTF8(bf.ReadNullTerminatedBytes())
 	return nil
 }
 

network/mhfpacket/msg_mhf_operate_warehouse.go

@@ -32,7 +32,7 @@ func (m *MsgMhfOperateWarehouse) Parse(bf *byteframe.ByteFrame, ctx *clientctx.C
 	lenName := bf.ReadUint8()
 	bf.ReadUint16() // Zeroed
 	if lenName > 0 {
-		m.Name = stringsupport.SJISToUTF8(bf.ReadNullTerminatedBytes())
+		m.Name, _ = stringsupport.SJISToUTF8(bf.ReadNullTerminatedBytes())
 	}
 	return nil
 }

network/mhfpacket/msg_mhf_send_mail.go

@@ -35,8 +35,8 @@ func (m *MsgMhfSendMail) Parse(bf *byteframe.ByteFrame, ctx *clientctx.ClientCon
 	bf.ReadUint16() // Zeroed
 	m.Quantity = bf.ReadUint16()
 	m.ItemID = bf.ReadUint16()
-	m.Subject = stringsupport.SJISToUTF8(bf.ReadNullTerminatedBytes())
-	m.Body = stringsupport.SJISToUTF8(bf.ReadNullTerminatedBytes())
+	m.Subject, _ = stringsupport.SJISToUTF8(bf.ReadNullTerminatedBytes())
+	m.Body, _ = stringsupport.SJISToUTF8(bf.ReadNullTerminatedBytes())
 	return nil
 }
 

network/mhfpacket/msg_mhf_update_guild_message_board.go

@@ -38,8 +38,8 @@ func (m *MsgMhfUpdateGuildMessageBoard) Parse(bf *byteframe.ByteFrame, ctx *clie
 		m.StampID = bf.ReadUint32()
 		m.TitleLength = bf.ReadUint32()
 		m.BodyLength = bf.ReadUint32()
-		m.Title = stringsupport.SJISToUTF8(bf.ReadBytes(uint(m.TitleLength)))
-		m.Body = stringsupport.SJISToUTF8(bf.ReadBytes(uint(m.BodyLength)))
+		m.Title, _ = stringsupport.SJISToUTF8(bf.ReadBytes(uint(m.TitleLength)))
+		m.Body, _ = stringsupport.SJISToUTF8(bf.ReadBytes(uint(m.BodyLength)))
 	case 1:
 		m.PostID = bf.ReadUint32()
 	case 2:
@@ -47,8 +47,8 @@ func (m *MsgMhfUpdateGuildMessageBoard) Parse(bf *byteframe.ByteFrame, ctx *clie
 		bf.ReadBytes(8)
 		m.TitleLength = bf.ReadUint32()
 		m.BodyLength = bf.ReadUint32()
-		m.Title = stringsupport.SJISToUTF8(bf.ReadBytes(uint(m.TitleLength)))
-		m.Body = stringsupport.SJISToUTF8(bf.ReadBytes(uint(m.BodyLength)))
+		m.Title, _ = stringsupport.SJISToUTF8(bf.ReadBytes(uint(m.TitleLength)))
+		m.Body, _ = stringsupport.SJISToUTF8(bf.ReadBytes(uint(m.BodyLength)))
 	case 3:
 		m.PostID = bf.ReadUint32()
 		bf.ReadBytes(8)

network/mhfpacket/msg_mhf_update_house.go

@@ -30,7 +30,7 @@ func (m *MsgMhfUpdateHouse) Parse(bf *byteframe.ByteFrame, ctx *clientctx.Client
 	bf.ReadUint8() // Zeroed
 	bf.ReadUint8() // Zeroed
 	bf.ReadUint8() // Password length
-	m.Password = stringsupport.SJISToUTF8(bf.ReadNullTerminatedBytes())
+	m.Password, _ = stringsupport.SJISToUTF8(bf.ReadNullTerminatedBytes())
 	return nil
 }