Add lastGeneratedColumn to typing for MappingItem

[samccone]

This is generated when someone calls computeColumnSpans so we mark the property as optional as well.

[coveralls]

Pull Request Test Coverage Report for Build 541

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 88.385%

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Totals
Change from base Build 539:	0.0%
Covered Lines:	824
Relevant Lines:	911

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💛 - Coveralls

[coveralls]

Pull Request Test Coverage Report for Build 541

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 88.385%

---

Totals
Change from base Build 539:	0.0%
Covered Lines:	824
Relevant Lines:	911

---

💛 - Coveralls

[coveralls]

Pull Request Test Coverage Report for Build 541

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 88.385%

---

Totals
Change from base Build 539:	0.0%
Covered Lines:	824
Relevant Lines:	911

---

💛 - Coveralls

[coveralls]

Pull Request Test Coverage Report for Build 541

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 88.385%

---

Totals
Change from base Build 539:	0.0%
Covered Lines:	824
Relevant Lines:	911

---

💛 - Coveralls

[jasonLaster]

Looks good to me.

[nikolay-borzov]

Any updates on this? Is there any reason why it's still pending merge?

[nikolay-borzov]

I think it should be

 lastGeneratedColumn: number | null;

If I understand code correctly the initial value is null then it can receive number values including Infinity

[jasonLaster]

This makes me think it is likely optional:

https://github.com/mozilla/source-map/blob/master/lib/wasm.js#L48-L51

[jasonLaster]

@ericmorand @samccone which do you think is the better typing:

lastGeneratedColumn?: number;

 lastGeneratedColumn: number | null;

[roblourens]

My interpretation is that lastGeneratedColumn: number | null; is correct, I agree with @nikolay-borzov

lastGeneratedColumn?: number; is equivalent to lastGeneratedColumn: number | undefined; but it is initialized as null.

[jasonLaster]

Thanks. Happy to update and land.

[ericmorand]

Can someone merge this and release a patch? It is a blocker for most of us using TypeScript.

EDIT: Well, not exactly a blocker, but having to extend MappingItem in our own code isn't exactly pretty:

type ValidMappingItem = MappingItem & {
    lastGeneratedColumn: number | null
}

[jasonLaster]

Thanks @ericmorand

[jasonLaster]

This makes me think it is likely optional:

https://github.com/mozilla/source-map/blob/master/lib/wasm.js#L48-L51