fix(findExports): filtering for named exports

[antfu]

The filtering introduced in #40 incidentally filtered out named exports like:

[
  { type: 'named', names: ['foo', /* ... */] },
  { type: 'named', names: ['bar', /* ... */] },
]

to becomes

[
  { type: 'named', names: ['bar', /* ... */] },
]

Due to both of the exports having undefined of the name property.

[danielroe]

Nice catch!