Fix TypeScript type errors in source files (#20)

TypeScript strict type checking was enabled but the codebase had 7 type
errors preventing successful compilation.

**Fixed type errors:**
- **decompress.js**: Added explicit `Buffer[]` type annotation for
chunks array to resolve implicit `any[]` inference
- **ffmpeg.js, node.js**: Added missing return statements to match JSDoc
`Promise<string>` declarations
- **main.js**: Added null check for `semver.coerce()` result and
eliminated redundant coerce call
- **request.js**: Added undefined check for `res.statusCode` before
comparison

**Example fix (main.js):**
```javascript
// Before: called coerce twice, missing null check
} else if (semver.valid(semver.coerce(options.version))) {
  options.version = semver.coerce(options.version).version;

// After: single call with proper null handling
} else {
  const coerced = semver.coerce(options.version);
  if (coerced && semver.valid(coerced)) {
    options.version = coerced.version;
```

All changes maintain existing runtime behavior while satisfying
TypeScript's strict type checking requirements.

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Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: ayushmanchhabra <14110965+ayushmanchhabra@users.noreply.github.com>

Author: Copilot

src/decompress.js

@@ -87,6 +87,7 @@ async function unzip(zippedFile, cacheDir) {
   for (const symlinkEntry of symlinks) {
     let entryPathAbs = path.join(cacheDir, symlinkEntry.filename);
     const readStream = await symlinkEntry.openReadStream();
+    /** @type {Buffer[]} */
     const chunks = [];
     readStream.on('data', (chunk) => chunks.push(chunk));
     await new Promise(resolve => readStream.on('end', resolve));

src/ffmpeg.js

@@ -35,4 +35,5 @@ export default async function ffmpeg(downloadUrl, version, platform, arch, cache
     );
 
     await request(url, ffmpegFileAbs);
+    return ffmpegFileAbs;
 }

src/main.js

@@ -54,10 +54,13 @@ async function get(options) {
     || options.version === "lts"
   ) {
     options.version = manifestData[options.version].slice(1);
-  } else if (semver.valid(semver.coerce(options.version))) {
-    options.version = semver.coerce(options.version).version;
   } else {
-    throw new Error('Expected "options.version" to be "latest", "stable", "lts" or a valid semver version. Received: ' + options.version);
+    const coerced = semver.coerce(options.version);
+    if (coerced && semver.valid(coerced)) {
+      options.version = coerced.version;
+    } else {
+      throw new Error('Expected "options.version" to be "latest", "stable", "lts" or a valid semver version. Received: ' + options.version);
+    }
   }
 
   if (options.flavor !== "normal" && options.flavor !== "sdk") {

src/node.js

@@ -45,4 +45,5 @@ export default async function nw(downloadUrl, version, cacheDir) {
   );
 
   await request(url, nwFileAbs);
+  return nwFileAbs;
 }

src/request.js

@@ -44,7 +44,7 @@ export default function request(url, filePath) {
       },
       (res) => {
         /* Redirect handling */
-        if (res.statusCode >= 300 && res.statusCode < 400 && res.headers.location) {
+        if (res.statusCode && res.statusCode >= 300 && res.statusCode < 400 && res.headers.location) {
           cleanup();
 
           const redirectedUrl = new URL(res.headers.location, parsedUrl).toString();