Apply eqeqeq lint rule

lib/extensions.js

@@ -96,11 +96,11 @@ function killAll(callback) {
   for (const n in processes) {
     ++counter;
     kill(processes[n], () => {
-      if (--counter == 0 && callback) callback();
+      if (--counter === 0 && callback) callback();
     });
     delete processes[n];
   }
-  if (--counter == 0 && callback) callback();
+  if (--counter === 0 && callback) callback();
 }
 
 exports.run = run;