CDMResultsAnalysisRunner hides exception leading to caching empty reports

Expected behavior

When experiencing a sql error from an achilles (Datasources) query drilldown, that drilldown should not cache any information.

Actual behavior

When an error is raised, the exception is logged, but an empty object is returned.

Steps to reproduce behavior

Difficult to reproduce because you have to craft your raw data to result in an error, but the troublesome line is found here:

    public JsonNode getDrilldown(JdbcTemplate jdbcTemplate,
                                 String domain,
                                 Integer conceptId,
                                 Source source) {
        ObjectNode objectNode = objectMapper.createObjectNode();
...
...
...
        } catch (Exception e) {
            log.error(e.getMessage(), e);
        }
        return objectNode;

The context is the getDrilldown() is called when we don't find data in the cache. The getDrilldown() will attempt to fetch the data from the source. For this example, the query resulted in an error, which is simply logged. The objectNode is still returned, which contains no data, and this 'no data' result is cached. There's no way to re-cache it without deleting the record from the webapi cache.

Start in src/main/java/org/ohdsi/webapi/report/CDMResultsAnalysisRunner.java at getDrilldown(), especially the catch block around line 287. Trace its caller and cache behavior to understand how an empty JsonNode is stored after a SQL error. Done means a failed drilldown does not produce a cacheable empty report.