Export Pages with options break in Sketch 55 Beta (78033)
When I export the page only, it seems to work fine, but if I don't export the page with options, it will cause an error. See below:
```
//Code 
var sketch = require('sketch/dom')
var document = sketch.getSelectedDocument()
var page = document.pages[0]

const options = { scales: '1', formats: 'png' }
sketch.export(page, options)

//Error
Error: An Obj-C exception occurred.
    at [native code] (/)
    at forEach[native code] (/)
    at /private/var/folders/qx/xt0zfls11dqbtnsvpyv_7nlhzqq83x/T/AppTranslocation/C335A74B-B188-40E4-99FF-DBC144F1DB05/d/Sketch Beta.app/Contents/Resources/SketchAPI_dom.js:1:122092
    at s (/private/var/folders/qx/xt0zfls11dqbtnsvpyv_7nlhzqq83x/T/AppTranslocation/C335A74B-B188-40E4-99FF-DBC144F1DB05/d/Sketch Beta.app/Contents/Resources/SketchAPI_dom.js:1:122135)
    at onRun (/Users/kyliediep/Library/Application Support/com.bohemiancoding.sketch3/Plugins/Untitled.sketchplugin:10:14)
  nativeException: ObjC method exportPage: requires 1 argument, but JavaScript passed 3 arguments
Script executed in 0.057511s
```
Specs:
Mac OSX 10.14.4
Sketch 55 (78033)