fix: improve error handling in cpFromInstance

- Handle symlinks with missing link_target
- Check settled flag to stop processing after rejection
- Nullify and destroy currentFile on write error

Author: rgarcia

src/lib/cp.ts

@@ -370,6 +370,11 @@ export async function cpFromInstance(cfg: CpConfig, opts: CpFromInstanceOptions)
     });
 
     ws.on('message', (data: Buffer | string) => {
+      // Don't process messages after the operation has settled
+      if (settled) {
+        return;
+      }
+
       // Try to parse as JSON first
       let msg: CpMessage | null = null;
       if (typeof data === 'string' || (Buffer.isBuffer(data) && !isBinaryData(data))) {
@@ -397,7 +402,13 @@ export async function cpFromInstance(cfg: CpConfig, opts: CpFromInstanceOptions)
 
               if (currentHeader.is_dir) {
                 fs.mkdirSync(targetPath, { recursive: true, mode: currentHeader.mode });
-              } else if (currentHeader.is_symlink && currentHeader.link_target) {
+              } else if (currentHeader.is_symlink) {
+                // Handle symlink - ensure link_target is present
+                if (!currentHeader.link_target) {
+                  doReject(new Error(`Symlink ${currentHeader.path} missing link target`));
+                  ws.close();
+                  return;
+                }
                 // Validate symlink target
                 const linkTarget = currentHeader.link_target;
                 if (path.isAbsolute(linkTarget) || path.normalize(linkTarget).startsWith('..')) {
@@ -417,7 +428,10 @@ export async function cpFromInstance(cfg: CpConfig, opts: CpFromInstanceOptions)
                 fs.mkdirSync(path.dirname(targetPath), { recursive: true });
                 currentFile = fs.createWriteStream(targetPath, { mode: currentHeader.mode });
                 // Add error handler to prevent unhandled 'error' events from crashing
+                const fileBeingWritten = currentFile;
                 currentFile.on('error', (err) => {
+                  fileBeingWritten.destroy();
+                  currentFile = null;
                   doReject(new Error(`Failed to write file ${targetPath}: ${err.message}`));
                   ws.close();
                 });