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);
+  }
+}

src/util/error_i18n.ts

@@ -0,0 +1,19 @@
+import {InjectedIntl} from 'react-intl';
+import {TopolaError} from './error';
+
+/**
+ * Returns a translated message for the given error. If the message can't be
+ * translated, the original error.message is returned.
+ */
+export function getI18nMessage(error: Error, intl: InjectedIntl): string {
+  if (!(error instanceof TopolaError)) {
+    return error.message;
+  }
+  return intl.formatMessage(
+    {
+      id: `error.${error.code}`,
+      defaultMessage: error.message,
+    },
+    error.args,
+  );
+}

src/util/gedcom_util.ts

@@ -1,4 +1,5 @@
 import {GedcomEntry, parse as parseGedcom} from 'parse-gedcom';
+import {TopolaError} from './error';
 import {
   JsonFam,
   JsonGedcomData,
@@ -245,7 +246,7 @@ export function convertGedcom(
     !json.fams ||
     !json.fams.length
   ) {
-    throw new Error('Failed to read GEDCOM file');
+    throw new TopolaError('GEDCOM_READ_FAILED', 'Failed to read GEDCOM file');
   }
 
   return {