Fix group image

mirai-core/src/commonMain/kotlin/net.mamoe.mirai/message/internal/MessageDataInternal.kt

@@ -167,7 +167,8 @@ fun MessageChain.toPacket(forGroup: Boolean): ByteReadPacket = buildPacket {
                 is At -> throw UnsupportedOperationException("At is not supported now but is expecting to be supported")
 
                 is Image -> buildPacket {
-                    if (forGroup) {
+                    when (id.value.length) {
+                        42 -> {
                             writeUByte(MessageType.GROUP_IMAGE.value)
 
                             //00 00 03 00 CB 02 00 2A 7B 46 36 31 35 39 33 42 35 2D 35 42 39 38 2D 31 37 39 38 2D 33 46 34 37 2D 32 41 39 31 44 33 32 45 44 32 46 43 7D 2E 6A 70 67
@@ -185,7 +186,9 @@ fun MessageChain.toPacket(forGroup: Boolean): ByteReadPacket = buildPacket {
                                 writeStringUtf8(id.value)
                                 writeUByte(0x41u)
                             }
-                    } else {
+                        }
+
+                        37 -> {
                             writeUByte(MessageType.FRIEND_IMAGE.value)
 
                             // 00 00 06 00 F3 02
@@ -253,6 +256,8 @@ fun MessageChain.toPacket(forGroup: Boolean): ByteReadPacket = buildPacket {
                                 writeUByte(0x41u)
                             }
                         }
+                        else -> error("Illegal ImageId ${id.value}")
+                    }
                 }
 
                 is PlainText -> buildPacket {