t.throws is not matching errors properly by Prototype

[maxcnunes]

Description

For few custom errors the t.throws weren't detecting the error type I passed to t.throws to assert with. The problem occurs because core-assert isn't giving the right match response on checking the error type based in the prototype. I have fixed that locally and now my tests are passing. Please accept my PR sindresorhus/core-assert#2 and bump it up on ava dependencies.

Test Source

  t.throws(
    () => deleteItem(initialState, operation),
    NotFoundObject
  );

Error Message & Stack Trace

Environment

Node.js v7.10.0
darwin 16.6.0
ava 0.22.0
npm 4.2.0

[novemberborn]

I'm not sure whether sindresorhus/core-assert#2 can be landed: sindresorhus/core-assert#2 (comment)

The plan is to refactor t.throws() to move away from core-assert: #1047 (comment)

Regardless, we'll enforce that constructors are extending Error. Is that the case with NotFoundObject? Going by AVA's error output it looks like it's a standalone class. That might also be why your test is currently failing.