We had a student reporting this problem. They described it thus...
"I have downloaded a course. Then when I go to the desktop app and attempt “offload all course data” it is coming up with this error message. I have also attempted to go into manage storage to remove the course and the same error appears. Unfortunately I then cannot download another course as I have already filled my two course quota."
This is a screenshot of the error...
Any ideas?
There's a very similar-looking report in the bug tracker: https://tracker.moodle.org/browse/MOBILE-3530
It has been traced to mod_hvp and a fix is in the works.
In JavaScript almost everything is an object, null and undefined are exceptions. This error occurs when a property is read or a function is called on an undefined variable. Undefined means that a variable has been declared but has not been assigned a value. In JavaScript, properties and functions can only belong to objects. Since undefined is not an object type, calling a function or a property on such a variable causes the TypeError: Cannot read property of undefined.
If you are not sure a variable that will always have some value, the best practice is to check the value of variables for null or undefined before using them. To avoid getting these types of errors, you need to make sure that the variables you are trying to read do have the correct value. This can be done in various ways. You can do if checks before dealing with objects whose values are bound to change:
if (myVar !== undefined) {
...
}
Or
if (typeof(myVar) !== 'undefined') {
...
}
