From dbd5ebcb4d49d572ef2eebc8dd138b92a036c7d2 Mon Sep 17 00:00:00 2001
From: Joe Fleming <w33ble@users.noreply.github.com>
Date: Fri, 8 Mar 2019 11:48:11 -0700
Subject: [PATCH] Fix: show actual errors on failed elements, handle null
 values from functions (#32600)

Closes https://github.com/elastic/kibana/issues/32356

This PR fixes two issues.

The first there was an issue filed, #32356:

- Show non-Boom errors instead of asking users to look at server logs
  - Also write the error to the server when asking them to look there

### Before

![](https://user-images.githubusercontent.com/404731/53673728-9368b180-3c46-11e9-912e-7aaff25d3ddf.png)
*If the function failed for some reason, this is all you'd ever see*

### After

![screenshot 2019-03-06 16 24 09](https://user-images.githubusercontent.com/404731/53921029-4d3b9580-402c-11e9-85bf-21ab31e952bc.png)
*Errors are shown to the user*

![screenshot 2019-03-06 16 26 16](https://user-images.githubusercontent.com/404731/53921130-a0154d00-402c-11e9-9cb5-102d360a69f8.png)
*Code errors bubble up correctly as well*

---

The other I didn't bother opening an issue for:

- Fixes issue where functions that return `null` produce an error message
  - `null` is a valid thing to return, it's only `undefined` that causes a problem
  - This was only a problem for server functions that return `null` (currently, none of them do)
  - Introduced in #31298
  - Discovered when I ran into casting problems (see https://github.com/elastic/kibana/issues/32597)

### Before

![screenshot 2019-03-06 16 18 17](https://user-images.githubusercontent.com/404731/53921039-562c6700-402c-11e9-9650-fc51d1f91643.png)

### After

![screenshot 2019-03-06 16 19 01](https://user-images.githubusercontent.com/404731/53921044-5cbade80-402c-11e9-9cde-fdb49334dcd0.png)
---
 .../interpreter/server/routes/server_functions.js      | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/src/legacy/core_plugins/interpreter/server/routes/server_functions.js b/src/legacy/core_plugins/interpreter/server/routes/server_functions.js
index cdd552e258ca9..c8a8f366a32c8 100644
--- a/src/legacy/core_plugins/interpreter/server/routes/server_functions.js
+++ b/src/legacy/core_plugins/interpreter/server/routes/server_functions.js
@@ -90,15 +90,19 @@ function runServerFunctions(server) {
         try {
           const result = await runFunction(server, handlers, fnCall);
 
-          if (result != null) {
-            return { id, statusCode: 200, result };
+          if (typeof result === 'undefined') {
+            return batchError(id, `Function ${fnCall.functionName} did not return anything.`);
           }
 
-          return batchError(id, `Function ${fnCall.functionName} did not return anything.`);
+          return { id, statusCode: 200, result };
         } catch (err) {
           if (Boom.isBoom(err)) {
             return batchError(id, err.output.payload, err.statusCode);
+          } else if (err instanceof Error) {
+            return batchError(id, err.message);
           }
+
+          server.log(['interpreter', 'error'], err);
           return batchError(id, 'See server logs for details.');
         }
       };