chore: replace nyc with c8

nyc doesn't support ESM, but c8 does and is a drop in replacement

See https://github.com/bcoe/c8

lib/copy-prototype-methods.mjs

@@ -10,10 +10,11 @@ var disallowedProperties = [
 
 // This branch is covered when tests are run with `--disable-proto=throw`,
 // however we cannot test both branches at the same time, so this is ignored
-/* istanbul ignore next */
+/* c8 ignore start */
 if (throwsOnProto) {
     disallowedProperties.push("__proto__");
 }
+/* c8 ignore stop */
 
 /**
  * Copies prototype methods into a new object that has no prototype
@@ -41,6 +42,6 @@ function copyPrototypeMethods(prototype) {
         return result;
     },
     Object.create(null));
-};
+}
 
 export default copyPrototypeMethods;

lib/deprecated.js

@@ -35,7 +35,6 @@ export function defaultMsg(packageName, funcName) {
  * @returns {undefined}
  */
 export function printWarning(msg) {
-    /* istanbul ignore next */
     if (typeof process === "object" && process.emitWarning) {
         // Emit Warnings in Node
         process.emitWarning(msg);

lib/global.mjs

@@ -3,17 +3,16 @@
  * @type {object} globalObject
  */
 var globalObject;
-
-/* istanbul ignore else */
 if (typeof global !== "undefined") {
     // Node
     globalObject = global;
-} else if (typeof window !== "undefined") {
+} /* c8 ignore start */ else if (typeof window !== "undefined") {
     // Browser
     globalObject = window;
 } else {
     // WebWorker
     globalObject = self;
 }
+/* c8 ignore stop */
 
 export default globalObject;

lib/throws-on-proto.mjs

@@ -12,11 +12,11 @@ try {
     // eslint-disable-next-line no-proto, no-unused-expressions
     object.__proto__;
     throwsOnProto = false;
-} catch (_) {
+} /* c8 ignore start */ catch (_) {
     // This branch is covered when tests are run with `--disable-proto=throw`,
     // however we can test both branches at the same time, so this is ignored
-    /* istanbul ignore next */
     throwsOnProto = true;
 }
+/* c8 ignore end */
 
 export default throwsOnProto;