fix(server/settings): write settings to a temp file then move to avoi…

…d corruption (#1067)

When writing the settings.json file ensure that the file is fully written by writing it to temporary
file before renaming it to the final settings path. This should prevent issues where the config gets
lost due to the file being corrupted.

server/lib/settings/index.ts

@@ -688,10 +688,9 @@ class Settings {
   }
 
   public async save(): Promise<void> {
-    await fs.writeFile(
-      SETTINGS_PATH,
-      JSON.stringify(this.data, undefined, ' ')
-    );
+    const tmp = SETTINGS_PATH + '.tmp';
+    await fs.writeFile(tmp, JSON.stringify(this.data, undefined, ' '));
+    await fs.rename(tmp, SETTINGS_PATH);
   }
 }