child_process: defer error to next tick

PR-URL: https://github.com/nodejs/node/pull/4670
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Santiago Gimeno <santiago.gimeno@gmail.com>
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Ilkka Myller <ilkka.myller@nodefield.com>

lib/internal/child_process.js

@@ -599,7 +599,7 @@ function setupChannel(target, channel) {
     if (typeof callback === 'function') {
       process.nextTick(callback, ex);
     } else {
-      this.emit('error', ex);  // FIXME(bnoordhuis) Defer to next tick.
+      process.nextTick(() => this.emit('error', ex));
     }
     return false;
   };
@@ -713,7 +713,7 @@ function setupChannel(target, channel) {
         if (typeof callback === 'function') {
           process.nextTick(callback, ex);
         } else {
-          this.emit('error', ex);  // FIXME(bnoordhuis) Defer to next tick.
+          process.nextTick(() => this.emit('error', ex));
         }
       }
     }