do not use finally

lib/mbox-export.js

@@ -43,19 +43,19 @@ async function mboxExport(auditHandler, audit) {
 
     setImmediate(() => {
         processExport()
-            .catch(err => {
+            .then(() => {
-                try {
-                    outputStream.write('\n' + err.message);
-                } catch (err) {
-                    //ignore
-                }
-            })
-            .finally(() => {
                 try {
                     outputStream.end();
                 } catch (err) {
                     // ignore at this point
                 }
+            })
+            .catch(err => {
+                try {
+                    outputStream.end('\n' + err.message);
+                } catch (err) {
+                    //ignore
+                }
             });
     });