Closing quicktype's stdout makes it output an error in some cases

Marks-iMac:quicktype schani$ ./script/quickesttype --src-lang schema --lang swift --just-types ./test/inputs/schema/vega-lite.schema   | head -n 4
import Foundation

struct VegaLite {
    /// URL to [JSON schema](http://json-schema.org/) for a Vega-Lite specification. Unless you

Issue in line 1390: quicktype cannot infer this type because there is no data about it in the input.
1390:     let on: Any?

Issue in line 1537: quicktype cannot infer this type because there is no data about it in the input.
1537:     let on: Any?

Issue in line 1585: quicktype cannot infer this type because there is no data about it in the input.
1585:     let on: Any?

Issue in line 4583: quicktype cannot infer this type because there is no data about it in the input.
4583:     let on: Any?
events.js:182
      throw er; // Unhandled 'error' event
      ^

Error: write EPIPE
    at exports._errnoException (util.js:1024:11)
    at WriteWrap.afterWrite [as oncomplete] (net.js:851:14)
Marks-iMac:quicktype schani$ ./script/quickesttype --lang swift --just-types ./test/inputs/json/samples/pokedex.json   | head -n 4
import Foundation

struct Pokedex {
    let pokemon: [Pokemon]
Marks-iMac:quicktype schani$ ./script/quickesttype --quiet --src-lang schema --lang swift --just-types ./test/inputs/schema/vega-lite.schema   | head -n 4
import Foundation

struct VegaLite {
    /// URL to [JSON schema](http://json-schema.org/) for a Vega-Lite specification. Unless you
events.js:182
      throw er; // Unhandled 'error' event
      ^

Error: write EPIPE
    at exports._errnoException (util.js:1024:11)
    at WriteWrap.afterWrite [as oncomplete] (net.js:851:14)