Fixes non-null assertion applied to type narrowed to never not issuing an error. #35863
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… return the declared type if the type was already narrowed to never. This was caused by the fact that getTypeWithFacts(resultType, TypeFacts.NEUndefinedOrNull) will return never both if resultType was already never and if resultType does not contain undefined or null. In the latter case returning the declaring type is correct, in the former case this causes something narrowed to never to still be typed as the original declared type.
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Fixed issue where non null assertion caused
getFlowTypeOfReferenceto return the declared type if the type was already narrowed to never.This was caused by the fact that
getTypeWithFacts(resultType, TypeFacts.NEUndefinedOrNull)will return never both ifresultTypewas alreadyneverand ifresultTypedoes not containundefinedornull. In the latter case returning the declaring type is correct, in the former case this causes something narrowed toneverto still be typed as the original declared type.Fixes #35431