Fix errors associated with using es6 instead of es2017

Author: Panger95

types/tsconfig.json

@@ -2,7 +2,7 @@
   "compilerOptions": {
     "module": "commonjs",
     "lib": [
-      "es6"
+      "es2017"
     ],
     "noImplicitAny": true,
     "noImplicitThis": true,
@@ -17,7 +17,6 @@
     "forceConsistentCasingInFileNames": true
   },
   "files": [
-    "index.d.ts",
     "tests.ts"
   ]
 }