Improve std Error compatibility

std/assembly/error.ts

@@ -1,12 +1,31 @@
 export class Error {
 
+  name: string = "Error";
   message: string;
   stack: string = ""; // TODO
 
   constructor(message: string = "") {
     this.message = message;
   }
+
+  toString(): string {
+    var message = this.message;
+    return message.length
+      ? this.name + ": " + message
+      : this.name;
+  }
 }
 
-export class RangeError extends Error {}
+export class RangeError extends Error {
-export class TypeError extends Error {}
+  constructor(message: string = "") {
+    super(message);
+    this.name = "RangeError";
+  }
+}
+
+export class TypeError extends Error {
+  constructor(message: string = "") {
+    super(message);
+    this.name = "TypeError";
+  }
+}