use-named-exports throws on FunctionDeclarations

Description

Running use-named-exports on this:

export default function foo(){}

throws:

 ERR file.js Transformation error ({ type: FunctionDeclaration, start: 15, end: 32, loc: null, id: [object Object], generator: false, async: false, params: , body: [object Object], expression: false, defaults: , rest: null, returnType: null, typeParameters: null, predicate: null } does not match field "init": Expression | null of type VariableDeclarator)
Error: { type: FunctionDeclaration, start: 15, end: 32, loc: null, id: [object Object], generator: false, async: false, params: , body: [object Object], expression: false, defaults: , rest: null, returnType: null, typeParameters: null, predicate: null } does not match field "init": Expression | null of type VariableDeclarator
    at addParam (/Users/seankelley/code/codemods/node_modules/ast-types/lib/types.js:450:27)
    at /Users/seankelley/code/codemods/node_modules/ast-types/lib/types.js:473:25
    at Array.forEach (<anonymous>)
    at Function.variableDeclarator (/Users/seankelley/code/codemods/node_modules/ast-types/lib/types.js:471:35)
    at Collection.exportDefaultAsNamed (/Users/seankelley/code/codemods/transforms/lib/helpers.js:160:73)
    at NodePath.<anonymous> (/Users/seankelley/code/codemods/transforms/use-named-exports.js:26:33)
    at NodePath.<anonymous> (/Users/seankelley/code/codemods/node_modules/jscodeshift/src/collections/Node.js:156:49)
    at /Users/seankelley/code/codemods/node_modules/jscodeshift/src/Collection.js:75:36
    at Array.forEach (<anonymous>)
    at Collection.forEach (/Users/seankelley/code/codemods/node_modules/jscodeshift/src/Collection.js:74:18)

Suggested Solution

Rewrite to the following:

export function foo(){}

or (assuming the file is called bar.js and we're doing the rename-export-after-file thing):

export function bar(){}

Help Needed

I'm not very familiar with jscodeshift so I hacked this poorly onto a fork of mine at https://github.com/seansfkelley/codemods/commit/bb28f9ed4cb865459ccfc3e22a35029c0c8bb95a.

It performs the second modification above, that is, to rename the exported function after the file.

I'm filing this issue to help anyone else who might stumble upon the same error. Thank you so much for publishing this repo; you saved me a bunch of work!

Start with transforms/lib/helpers.js at exportDefaultAsNamed and the caller in transforms/use-named-exports.js, then run the provided default FunctionDeclaration example to reproduce the ast-types error. Done means the transform handles the example and produces one of the suggested named-export forms without throwing.