Error: Read error for params.advancements.advancementMapping.3.value.displayData.icon.unknown.default.nbtData.type : 109 is not in the mappings value

Hello, I'm using node-minecraft-protocol to help debug packet parsing for another program since it (along with minecraft-data) appears to be the most complete repository of protocol data, but there's one packet I encountered which it cannot parse:

last-packet.zip

This is an advancement packet for 1.12.2. Script to try to parse it:

const mc=require('minecraft-protocol');
const d=mc.createDeserializer({version:"1.12.2", state:mc.states.PLAY});
d.on('data',(parsed)=>{
  console.log(JSON.stringify(parsed, null, ''));
  console.log(parsed.data.params);
});
d.write(require('fs').readFileSync('last-packet'));

Run with DEBUG=minecraft-protocol node try5.js, crashes with "params.advancements.advancementMapping.3.value.displayData.icon.unknown.default.nbtData.type : 109 is not in the mappings value", full stack trace:

events.js:183
      throw er; // Unhandled 'error' event
      ^

Error: Read error for params.advancements.advancementMapping.3.value.displayData.icon.unknown.default.nbtData.type : 109 is not in the mappings value
    at ProtoDef.readMapper (node-minecraft-protocol/node_modules/protodef/src/datatypes/utils.js:30:34)
    at ProtoDef.read (node-minecraft-protocol/node_modules/protodef/src/protodef.js:36:25)
    at ProtoDef.read (node-minecraft-protocol/node_modules/protodef/src/protodef.js:110:29)
    at tryDoc (node-minecraft-protocol/node_modules/protodef/src/datatypes/structures.js:45:32)
    at tryCatch (node-minecraft-protocol/node_modules/protodef/src/utils.js:50:16)
    at tryDoc (node-minecraft-protocol/node_modules/protodef/src/utils.js:54:10)
    at typeArgs.forEach (node-minecraft-protocol/node_modules/protodef/src/datatypes/structures.js:44:5)
    at Array.forEach (<anonymous>)
    at ProtoDef.readContainer (node-minecraft-protocol/node_modules/protodef/src/datatypes/structures.js:43:12)
    at ProtoDef.read (node-minecraft-protocol/node_modules/protodef/src/protodef.js:36:25)

Looking at the code, it appears the "mappings value" it refers to is the NBT types, which 109 isn't valid for, so this suggests a problem earlier in the parsing.

If it matters, this packet was captured from SevTech: Ages 3.11 server (currently top #3 modpack on Curseforge with 1,945,358 downloads. No packet parsing discrepancies found in the top 1st and 2nd packs but they are both for 1.7.10.). This server is modded with Forge so it is possible it or another mod changed the advancement packet structure, I don't think node-minecraft-protocol/minecraft-data is inaccurate vs vanilla, but would be great if it could support this likely modded packet somehow. I'll attach my notes on attempting to decode it below.

Start by running the provided deserializer script with the attached last-packet capture for version 1.12.2 in the PLAY state. Trace the advancement packet (id 4d) through the Protodef stack locations shown in node_modules/protodef and compare it with the partial decode, especially the advancement display and NBT type fields. Done means the capture no longer produces the reported mapping error, with tests or reproduction notes covering the result.