Bug Reports:
Unable to parse responseText of JSONP in a error handler.

• What do you expect to happen? Able to parse the JSON
• What actually happens? Get a parsing error
• Which browsers are affected - Chrome/Firefox?

Currently using Backbone and JQuery. Recently have upgraded from 3.3.1 to 3.5.1. Essentially, backbone is using a jsonp request to delete a model but expecting a 409 due to the model being unable to be deleted. It works as expected and end up in the error handler but the responseJson is not present. I have walked through the stack trace difference between 3.3.1 & 3.5.1. The reason seems to be a parsing error:

error: Error: jQuery35109401972421271656_1597775421415 was not called at Function.error (3.5.1/jquery.js:334:9) at s.converters.script json (3.5.1/jquery.js:10232:12) at ajaxConvert (jquery/3.5.1/jquery.js:9260:19) at done (3.5.1/jquery.js:9736:15) at XMLHttpRequest.<anonymous> (3.5.1/jquery.js:10047:9) message: "jQuery35109401972421271656_1597775421415 was not called" stack: "Error: jQuery35109401972421271656_1597775421415 was not called state: "parsererror"

From walking through the stacktrace it seems related to - 50871a5