Skip assigning __proto__ instead of rejecting it during validation

src/packages/create/index.js

@@ -11,6 +11,13 @@ const forbidSpecialProperties = require("./validators/forbid-special-properties"
 const isErrorConstructor = require("./validators/is-error-constructor");
 const isContextSchema = require("./validators/is-context-schema");
 
+function safeAssign(a, ... rest) {
+	let previousPrototype = a.__proto__;
+	Object.assign(a, ... rest);
+	a.__proto__ = previousPrototype;
+	return a;
+}
+
 module.exports = function createCustomErrorType(_name, _options) {
 	let [ name, options ] = validateArguments(arguments, {
 		name: [ required, isString ],
@@ -48,7 +55,7 @@ module.exports = function createCustomErrorType(_name, _options) {
 		}
 
 		ErrorConstructor._assignDefaultProperties(this);
-		Object.assign(this, context);
+		safeAssign(this, context);
 	};
 
 	ErrorConstructor._assignDefaultProperties = function (errorObject) {
@@ -58,7 +65,7 @@ module.exports = function createCustomErrorType(_name, _options) {
 			options.inheritsFrom._assignDefaultProperties(errorObject);
 		}
 
-		Object.assign(errorObject, options.context);
+		safeAssign(errorObject, options.context);
 	};
 	
 	ErrorConstructor.prototype = Object.create(options.inheritsFrom.prototype);

src/packages/create/validators/forbid-special-properties.js

@@ -6,13 +6,12 @@ const syncpipe = require("syncpipe");
 const wrapError = require("@validatem/wrap-error");
 const forbidden = require("@validatem/forbidden");
 const allowExtraProperties = require("@validatem/allow-extra-properties");
-const ValidationError = require("@validatem/error");
 
 const reservedProperties = require("../../reserved-properties");
 
 let forbidSpecialProperty = wrapError("Reserved property name cannot be used", forbidden);
 
-let baseChecks = syncpipe(reservedProperties, [
+module.exports = syncpipe(reservedProperties, [
 	(_) => _.filter((property) => property !== "constructor"),
 	(_) => _.map((property) => {
 		// NOTE: It is very important that `forbidSpecialProperty` below is wrapped in an array. Otherwise, for the `__proto__` property, it will actually treat the entire rules object as a validatem-special object due to its __proto__ being set directly to an object with the validatem-special marker... We're hacking around this by wrapping it in an array instead, which will not register as such. It's really a hack, though.
@@ -21,12 +20,3 @@ let baseChecks = syncpipe(reservedProperties, [
 	(_) => fromEntries(_),
 	(_) => allowExtraProperties(_)
 ]);
-
-module.exports = [
-	baseChecks,
-	(value) => {
-		if (value.__proto__ != null) {
-			return new ValidationError("Reserved property name __proto__ cannot be used");
-		}
-	}
-];