doc(serverless): add workaround for return data that is array/list (#5570)

* chore: add workaround for return data that is array/list

* chore: feedback

Co-authored-by: Scott Anderson <sanderson@users.noreply.github.com>

* chore: feedback

Co-authored-by: Scott Anderson <sanderson@users.noreply.github.com>

* Update content/influxdb/cloud-serverless/query-data/troubleshoot-and-optimize/troubleshoot.md

---------

Co-authored-by: Scott Anderson <sanderson@users.noreply.github.com>

content/influxdb/cloud-serverless/query-data/troubleshoot-and-optimize/troubleshoot.md

@@ -28,6 +28,14 @@ If a query doesn't return any data, it might be due to the following:
 - Your data falls outside the time range (or other conditions) in the query--for example, the InfluxQL `SHOW TAG VALUES` command uses a default time range of 1 day.
 - The query (InfluxDB server) timed out.
 - The query client timed out.
+- The query return type is not supported by the client library.
+  For example, array or list types may not be supported.
+  In this case, use `array_to_string()` to convert the array value to a string--for example:
+
+  ```sql
+  SELECT array_to_string(array_agg([1, 2, 3]), ', ')
+  ```
+
 
 If a query times out or returns an error, it might be due to the following: