Consider handling typescript-eslint-specific AST

[vhfmag]

The team I work on is migrating a Flow project to Typescript, and we are trying to keep our ESLint setup by using typescript-eslint, but things were not working out as expected.

After some debugging, we found out that the issue was within jsx-ast-utils, which didn't correctly handle JSX attributes in the form of atribute={value!} (where ! is a Typescript non-null assertion, i.e. it tells Typescript to assume that value is neither null or undefined). It crashed here, more specifically. The issue is that @typescript-eslint/typescript-estree exposes it as a TSNonNullExpression node with value's AST as node.expression.

For our codebase, simply adding

if (type === "TSNonNullExpression") {
  expression = expression.expression;
  type = expression.type;
}

before that check made everything work. It's a fairly large React codebase, so I guess it's fair to assume there would be little additional work.

I would be happy to come up with a PR if the project sees this as desirable. Thanks!

[ljharb]

Seems desirable to me.

[vhfmag]

Just submitted #72 :)