1353067 - Improve "is not a non-null object" message

Status: NEW

(Core :: JavaScript Engine, defect, P3)

Description

[Florian Scholz (Open Web Docs)]

See https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Errors/No_non-null_object (which needs updating, if we update our message)

At least for me, "x is not a non-null object" is kind of hard to understand.

Case 1: Object.defineProperty({}, 'key', 1);
Firefox: TypeError: 1 is not a non-null object
Chrome: Uncaught TypeError: Property description must be an object: 1

Chrome makes more sense and actually tells you that the property description object is what is missing here.

Case 2: new WeakSet().add('foo');
Firefox: TypeError: "foo" is not a non-null object
Chrome: Uncaught TypeError: Invalid value used in weak set

Chrome isn't too helpful here either. 
Maybe "TypeError: WeakSet value must be an object, got a string"

There might be more cases, search for JSMSG_NOT_NONNULL_OBJECT.

I think in general, "must be x, but got y" is most helpful. We have such error messages elsewhere.

Comment 1

[kikuchi1024r]

Attachment: bug1353067.patch

Change error message of case1. 
case2 is already solved.
https://bugzilla.mozilla.org/show_bug.cgi?id=7747
Now, the error message is below.
```
js> Object.defineProperty({},'key',1);
typein:1:1 TypeError: ({}) is not a non-null object
```
descriptor must be object.

In this patch, the error message is below.
```
js> Object.defineProperty({},'key',1);
typein:1:1 TypeError: descriptor must be an object, got number '1'

```
 the grammer is "{0} must be an object, got {1} '{2}'", and when you use defineProperty, {0} is "descriptor" ,{1} is the type of descriptor, and {2} is the descripter which you write down literely.

Comment 2

[kikuchi1024r]

sorry, I mistook the URL
https://bugzilla.mozilla.org/show_bug.cgi?id=774744

Comment 3

[Tooru Fujisawa [:arai]]

Comment on attachment 8925808 [details] [diff] [review]
bug1353067.patch

Review of attachment 8925808 [details] [diff] [review]:
-----------------------------------------------------------------

Thank you for your patch.

The change itself looks good.

Then, since there are several more places [1] that uses JSMSG_NOT_NONNULL_OBJECT,
it would be nice to file dedicated bug for this single fix.
can you file a bug for this and attach this patch there?

[1] https://dxr.mozilla.org/mozilla-central/search?q=JSMSG_NOT_NONNULL_OBJECT&case=true&=mozilla-central