minimal support for bigint

.eslintrc.json

@@ -3,7 +3,7 @@
   "plugins": ["@typescript-eslint"],
   "parser": "@typescript-eslint/parser",
   "env": {
-    "es6": true,
+    "es2020": true,
     "node": true,
     "browser": true
   },

src/scales.js

@@ -512,7 +512,7 @@ export function coerceNumbers(values) {
 // since the result will be stored in a Float64Array and we don’t want null to
 // be coerced to zero.
 export function coerceNumber(x) {
-  return x == null ? NaN : +x;
+  return x == null ? NaN : Number(x);
 }
 
 // When coercing strings to dates, we only want to allow the ISO 8601 format