fix(firestore): fix an issue that would cause FieldValue.increment to be interpreted as double

[Lyokone]

Description

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Related Issues

closes #12436

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[ZippyRainbow]

Hi @Lyokone,
This didn't seem to fix the issue with the int increment as it is still resulting in a double stored in firestore.
increment(1) should result in a stored value of a int
increment(1.0) should result in a stored value of a double.

[estien]

Hi @Lyokone, This didn't seem to fix the issue with the int increment as it is still resulting in a double stored in firestore. increment(1) should result in a stored value of a int increment(1.0) should result in a stored value of a double.

I can confirm this as an ongoing issue still. Since the value type changes from int to double in Firestore whenever FieldValue.increment is invoked, I have to patch the document using onDocumentWritten from Firebase Functions until a fix is in place.

Can this be looked at @Lyokone please?