fix: #3737

[AyushRawal]

return valid json with npm search module_not_exists --json

References

Fixes #3737

[wraithgar]

Can a test be added to test/lib/search.js that covers this case?

[AyushRawal]

@wraithgar Does this look good ?

t.test('search <invalid-module> --json', (t) => {
  const src = new Minipass()
  src.objectMode = true

  npm.flatOptions.json = true
  config.json = true
  const libnpmsearch = {
    stream () {
      return src
    },
  }

  const Search = t.mock('../../lib/search.js', {
    ...mocks,
    libnpmsearch,
  })
  const search = new Search(npm)

  search.exec(['foo'], (err) => {
    if (err)
      throw err

    t.equal(result, '\n[]\n', 'should have expected empty square brackets')

    config.json = false
    t.end()
  })

  src.end()
})

[wraithgar]

Yeah I think that should do it, a src that ends w/o sending any data, that's the code path here.