[Fix] Uint8Array.prototype.setFromBase64: avoid invoking toString o…

…n a non-string `string` argument

Also:
 - add test coverage from tc39/test262#3994

.eslintrc

@@ -18,6 +18,7 @@
 			"capIsNewExceptions": [
 				"FromBase64",
 				"FromHex",
+				"DetachArrayBuffer",
 				"Get",
 				"GetIntrinsic",
 				"GetOptionsObject",

Uint8Array.prototype.setFromBase64/implementation.js

@@ -29,7 +29,7 @@ module.exports = function setFromBase64(string) {
 	ValidateUint8Array(into); // step 2
 
 	if (typeof string !== 'string') {
-		throw new $TypeError('`string` is not a string: ' + string); // step 3
+		throw new $TypeError('`string` is not a string: ' + typeof string); // step 3
 	}
 
 	var opts = GetOptionsObject(arguments.length > 1 ? arguments[1] : void undefined); // step 4
@@ -41,7 +41,7 @@ module.exports = function setFromBase64(string) {
 	}
 
 	if (typeof alphabet !== 'string') {
-		throw new $TypeError('`alphabet` is not a string: ' + alphabet); // step 7
+		throw new $TypeError('`alphabet` is not a string: ' + typeof alphabet); // step 7
 	}
 
 	if (alphabet !== 'base64' && alphabet !== 'base64url') {

package.json

@@ -69,6 +69,7 @@
 		"evalmd": "^0.0.19",
 		"for-each": "^0.3.3",
 		"in-publish": "^2.0.1",
+		"is-core-module": "^2.13.1",
 		"npmignore": "^0.3.1",
 		"nyc": "^10.3.2",
 		"object-inspect": "^1.13.1",