GASRetry - Exponential backoff JavaScript implementation for Google Apps Script (Library project key: "MGJu3PS2ZYnANtJ9kyn2vnlLDhaBgl_dE")

gistfile1.js

/**
* Invokes a function, performing up to 5 retries with exponential backoff.
* Retries with delays of approximately 1, 2, 4, 8 then 16 seconds for a total of 
* about 32 seconds before it gives up and rethrows the last error. 
* See: https://developers.google.com/google-apps/documents-list/#implementing_exponential_backoff 
<h3>Examples:</h3>
<pre>//Calls an anonymous function that concatenates a greeting with the current Apps user's email
var example1 = GASRetry.call(function(){return "Hello, " + Session.getActiveUser().getEmail();});
</pre><pre>//Calls an existing function
var example2 = GASRetry.call(myFunction);
</pre><pre>//Calls an anonymous function that calls an existing function with an argument
var example3 = GASRetry.call(function(){myFunction("something")});
</pre><pre>//Calls an anonymous function that invokes DocsList.setTrashed on myFile and logs retries with the Logger.log function.
var example4 = GASRetry.call(function(){myFile.setTrashed(true)}, Logger.log);
</pre>
*
* @param {Function} func The anonymous or named function to call.
* @param {Function} optLoggerFunction Optionally, you can pass a function that will be used to log 
to in the case of a retry. For example, Logger.log (no parentheses) will work.
* @return {*} The value returned by the called function.
*/
function call(func, optLoggerFunction) {
  for (var n=0; n<6; n++) {
    try {
      return func();
    } catch(e) {
      if (optLoggerFunction) {optLoggerFunction("GASRetry " + n + ": " + e)}
      if (n == 5) {
        throw e;
      } 
      Utilities.sleep((Math.pow(2,n)*1000) + (Math.round(Math.random() * 1000)));
    }    
  }
}

Hi, I'm triyng to write this retry loop into the code below but I can't seem to get it working. Please see below. Any help would be greatly appreciated as I've beeb wrapping my head around this for days now with no luck. I've left it clean without any changes to show the original script. The error I keep getting is '(TypeError: Cannot call method "getChild" of null.' and I want to retry the function to reduce the error:

function update_(trigger) {
try {
var response,
image,
count = 0,
last = false,
data = productSheet.getDataRange().getValues();

for (var i = 2, len = data.length; i < len && !isTimeUp_(); i++) {
  last = i === len - 1;

  if (
    isEmpty_(data[i][0]) ||
    data[i][3].match('TypeError: Cannot call method "getChild" of null.'/i) ||
    isRecentlyProcessed_(data[i][9])
  ) {
    continue;
  }

  response = fetchPrice_(data[i][0]);

  if (response && response.status === '200') {


    productSheet
      .getRange(i + 1, 1, 1, 11)
      .setValues([
        [
          response.url,
          data[i][1],
          response.iseligible,
          response.title,
           response.iseligible,
          response.price,
          response.iseligible,
          response.iseligible,
          response.availability,
          new Date(),
          response.iseligible,
        ]
      ]);

    if (!trigger) {
      ss.toast('Processing #' + (i + 1) + '. ' + response.title);
      if (i % 15 === 0) SpreadsheetApp.flush();
    } else {
      if (
        !isEmpty_(data[i][1]) &&
        !isEmpty_(data[i][11]) &&
        sendPriceAlert_(data[i], response)
      )
        productSheet.getRange(i + 1, 12).setValue(response.price);
    }
  } else {
    productSheet
      .getRange(i + 1, 4, 1, 8)
      .setValues([[response.error, '', '', '', '', '', new Date(), '']]);
  }
}

} catch (e) {
Logger.log(e.toString());
}
}

function call_(func) {
for (var n = 0; n < 6; n++) {
try {
return func();
} catch (e) {
if (n == 5) {
throw e;
}
Utilities.sleep(Math.pow(2, n) * 1000 + Math.round(Math.random() * 1000));
}
}
}

Using this library makes autocomplete to dissapear.. Any idea how to get it back ?
Ex:
var ss = call(function(){return SpreadsheetApp.getActiveSpreadsheet()})
var sh = ss.// no autocomplete available here