In src/gholder.c, the function set_root_metrics has the following code:

static int
set_root_metrics (GRawDataItem item, GModule module, datatype type, GMetrics ** nmetrics) {
    ...
    uint32_t hits = 0;
    if (map_data (module, item, type, &data, &hits) == 1)
        return 1;
    ...
    metrics->avgts.nts = cumts / hits;

On successful return, the function map_data may set hits to item.hits, and if item.hits is 0, then there is a divide by zero problem. I think this case maybe possible. For example, function parse_raw_data seems to leave the field hits in GRawDataItem as 0.