A better way for handling PhantomJS exits

Author: Micah Bule

lib/pdf.js

@@ -117,13 +117,27 @@ PDF.prototype.exec = function PdfExec (callback) {
     // If we don't have an exit code, we kill the process, ignore stderr after this point
     if (code === null) kill(child, onData, onError)
 
-    if (!data) {
-      if (!err && code) err = new Error("html-pdf: Received the exit code '" + code + "'")
-      else if (!err) err = new Error('html-pdf: Unknown Error')
-
+    // 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 !== 0) {
+
+      var error = null;
+
+      if (err) {
+        // Rudimentary checking if err is an instance of the Error class
+        error = err instanceof Error ? err : new Error(err)
+      } else {
+        // This is to catch the edge case of having a exit code value of 1 but having no error
+        error = new Error('html-pdf: Unknown Error')
+      }
+
+      // Append anything caught from the stderr
       var postfix = stderr.length ? '\n' + Buffer.concat(stderr).toString() : ''
       if (postfix) err.message += postfix
-      return callback(err, null)
+
+      return callback(error);
     }
 
     callback(null, data)