Merge pull request #5 from ZerozAndOnes/comment-fix

Comments fix

Author: ZerozAndOnes

lib/pdf.js

@@ -120,7 +120,6 @@ PDF.prototype.exec = function PdfExec (callback) {
     if (code === null) kill(child, onData, onError)
 
     // Since code has a truthy/falsy value of either 0 or 1, check for existence first.
-    // Ignore if code has a value of 0 since that means PhantomJS has executed and exited successfully.
     // Also, as per your script and standards, having a code value of 1 means one can always assume that
     // an error occured.
     if (((typeof code !== 'undefined' && code !== null) && code !== 0) || err || (code === 0 && !data)) {
@@ -153,6 +152,9 @@ PDF.prototype.exec = function PdfExec (callback) {
 
   // An exit event is most likely an error because we didn't get any data at this point
   child.on('close', respond)
+  // According to child process documentation (https://nodejs.org/docs/latest-v14.x/api/child_process.html#child_process_event_exit), 
+  // exit event can fire before stdio is closed. Thus, it's probably not a good idea to subscribe to exit event at all.
+  // on('close') above should be sufficient
   // child.on('exit', respond)
 
   var config = JSON.stringify({html: this.html, options: this.options})