Translated error messages

src/util/error.ts

@@ -0,0 +1,10 @@
+/** Error class adding an error code used for i18n. */
+export class TopolaError extends Error {
+  constructor(
+    public readonly code: string,
+    message: string,
+    public readonly args: {[key: string]: string} = {},
+  ) {
+    super(message);
+  }
+}