The JavaScript exception "null (or undefined) has no properties" occurs when you attempt to access properties of null and undefined. They don't have any.
Message
TypeError: Unable to get property {x} of undefined or null reference (Edge)
TypeError: null has no properties (Firefox)
TypeError: undefined has no properties (Firefox)
Error type
What went wrong?
Both, null and undefined, have no properties you could access.
Examples
null and undefined have no properties
null.foo; // TypeError: null has no properties undefined.bar; // TypeError: undefined has no properties