import SettingData, { DefaultSettingData } from '../shared/SettingData';

export const load = async(): Promise<SettingData> => {
  let { settings } = await browser.storage.local.get('settings');
  if (!settings) {
    return DefaultSettingData;
  }
  try {
    return SettingData.valueOf(settings as any);
  } catch (e) {
    console.error('unable to load settings', e);
    return DefaultSettingData;
  }
};

export const save = (data: SettingData) => {
  return browser.storage.local.set({
    settings: data.toJSON(),
  });
};

import SettingData, { DefaultSettingData } from '../shared/SettingData';

export const load = async(): Promise<SettingData> => {
  let { settings } = await browser.storage.local.get('settings');
  if (!settings) {
    return DefaultSettingData;
  }
  return SettingData.valueOf(settings as any);
};

export const save = (data: SettingData) => {
  return browser.storage.local.set({
    settings: data.toJSON(),
  });
};

--- 
+++ 
@@ -5,7 +5,12 @@
   if (!settings) {
     return DefaultSettingData;
   }
-  return SettingData.valueOf(settings as any);
+  try {
+    return SettingData.valueOf(settings as any);
+  } catch (e) {
+    console.error('unable to load settings', e);
+    return DefaultSettingData;
+  }
 };
 
 export const save = (data: SettingData) => {
Use default settings on loading failure
