[Bug]: Using HttpPart results in error in emitter-server-js

[experimentlife]

Describe the bug

import "@typespec/http";

using Http;

@error
model Error<T extends string> {
  code: T;
  message: string;
  details?: Record<string>;
  timestamp: utcDateTime;
}

/**
 * Standard success response
 */
model Result<T extends string> {
  code: T;
  message: string;
  details?: Record<string>;
  timestamp: utcDateTime;
}

model AttachmentError is Error<"invalid-attachment" | "empty-attachment">;
model AttachmentResult is Result<"added-attachment">;

interface x {
@route("{id}/addAttachment") @post addAttachment(@path id: string, @header contentType: "multipart/form-data", 
    @multipartBody body: {
      recepientRequestId: HttpPart<string>;
      name: HttpPart<string>;
      type: HttpPart<string>;
      data: HttpPart<File>;
    },) : AttachmentError | AttachmentResult;
}

The above when using a HttpPart results in

Emitter "@typespec/http-server-js" crashed! This is a bug.
Please file an issue at https://github.com/microsoft/typespec/issues

Error: UNREACHABLE: HttpPart must have a Model argument
    at emitWellKnownModel (file:///C:/r/prod/pserv/PServAgentService/node_modules/@typespec/http-server-js/dist/src/common/model.js:105:23)
    at emitTypeReference (file:///C:/r/prod/pserv/PServAgentService/node_modules/@typespec/http-server-js/dist/src/common/reference.js:55:24)
    at emitModel (file:///C:/r/prod/pserv/PServAgentService/node_modules/@typespec/http-server-js/dist/src/common/model.js:47:31)
    at emitModel.next (<anonymous>)
    at emitDeclaration (file:///C:/r/prod/pserv/PServAgentService/node_modules/@typespec/http-server-js/dist/src/common/declaration.js:21:20)
    at emitDeclaration.next (<anonymous>)
    at completePendingDeclarations (file:///C:/r/prod/pserv/PServAgentService/node_modules/@typespec/http-server-js/dist/src/ctx.js:111:28)
    at emitRawServerOperation (file:///C:/r/prod/pserv/PServAgentService/node_modules/@typespec/http-server-js/dist/src/http/server/index.js:67:5)
    at emitRawServerOperation.next (<anonymous>)
    at emitRawServer (file:///C:/r/prod/pserv/PServAgentService/node_modules/@typespec/http-server-js/dist/src/http/server/index.js:44:16)

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Library Version                0.58.0-alpha.11
TypeSpec Compiler Version      0.67.2
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Reproduction

Run the sample provided above in the description

Checklist

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• Check that there isn't already an issue that request the same bug to avoid creating a duplicate.
• Check that this is a concrete bug. For Q&A open a GitHub Discussion.
• The provided reproduction is a minimal reproducible example of the bug.