fix: more types

This seems to be the way you're supposed to write overloads, but it does feel wrong.

Author: lishaduck

lib/app-wrapper.js

@@ -109,9 +109,7 @@ function subscribe(port) {
 function unsubscribe(port) {
   // eslint-disable-next-line promise/prefer-await-to-callbacks -- Callbacks are still needed here.
   return (callback) => {
-    listeners[port] = listeners[port].filter(
-      (/** @type {Listened<unknown>} */ fn) => fn === callback
-    );
+    listeners[port] = listeners[port].filter((fn) => fn === callback);
   };
 }
 

lib/parse-elm.js

@@ -63,10 +63,12 @@ function terminateWorkers() {
 async function parse(elmParserPath, source) {
   return await new Promise((resolve, reject) => {
     const availableWorker = findInactiveWorker();
+
     /** @type {ParseJob} */
     const queueItem = {
       source,
       elmParserPath,
+
       callback: (/** @type {Error | undefined} */ error, result) => {
         if (error === undefined) {
           resolve(result);

lib/types/parse-elm.ts

@@ -5,12 +5,11 @@ import type {SendPort, SubscribePort} from './promisify-port.js';
 export type ParseJob = {
   elmParserPath: Path;
   source: Source;
-  callback: Callback;
-};
 
-type Callback = {
-  (error: Error): void;
-  (error: undefined, result: Ast): void;
+  callback: {
+    (error: Error): void;
+    (error: undefined, result: Ast): void;
+  };
 };
 
 export type ParserApp = {