Use make-promises-safe to catch unhandled rejections in tests

packages/json-schemas/package.json

@@ -2,7 +2,7 @@
     "name": "@0xproject/json-schemas",
     "version": "0.7.23",
     "engines": {
-        "node" : ">=6.12"
+        "node": ">=6.12"
     },
     "description": "0x-related json schemas",
     "main": "lib/src/index.js",
@@ -61,6 +61,7 @@
         "copyfiles": "^1.2.0",
         "dirty-chai": "^2.0.1",
         "lodash.foreach": "^4.5.0",
+        "make-promises-safe": "^1.1.0",
         "mocha": "^4.0.1",
         "npm-run-all": "^4.1.2",
         "nyc": "^11.0.1",

packages/json-schemas/test/schema_test.ts

@@ -2,6 +2,7 @@ import { BigNumber } from '@0xproject/utils';
 import * as chai from 'chai';
 import * as dirtyChai from 'dirty-chai';
 import forEach = require('lodash.foreach');
+import 'make-promises-safe';
 import 'mocha';
 
 import { schemas, SchemaValidator } from '../src/index';