npm install failing saying "no member named isNearDeath"

node-sass is a 'native' module (i.e. some parts of it are implemented in a language that compiles down to machine code - in this case, C++). This means that it makes use of Node's native APIs, which can change from version to version. As such, native modules will often only work with certain versions of Node, and require updates when the version of Node changes.

node-sass is no exception to this rule, and their README states that if you wish to use Node v12, you must use node-sass v4.12.0 or higher.

I had a similar issue and it could be due to a Node upgrade: in fact I was able to solve it by downgrading from version 12 to 10, as discussed in this thread.