Fixed the issue that the socket is closed too early (kylefarris#127)

index.js

@@ -2256,6 +2256,7 @@ class NodeClam {
                     // The transform stream has dried up
                     .on('end', () => {
                         if (this.settings.debugMode) console.log(`${this.debugLabel}: The transform stream has ended.`);
+                        transform.end();
                     })
                     .on('error', err => {
                         console.error(`${this.debugLabel}: Error emitted from transform stream: `, err);