[Metrics ServerApp] - Some endpoints throwing an exception

[Jklawreszuk]

Release Type: Official Release/GitHub
Version: Any
Platform(s): Any
Describe the bug: As a title suggests

To Reproduce
Steps to reproduce the behavior:

1. Run app or just go to metrics.stride3d.net website.
2. You'll figure out that some plots don't render anything (this is because js hasn't received the data from EP representing that chart).
3. Make HTTP GET request to any EP where plot's data is missing. Example statistic "quits per month" :

HTTP GET https://metrics.stride3d.net/api/get-quitting-count

• response:

500 INTERNAL ERROR
{
    "message": "An error has occurred."
}

Additional information
If you take a look at first line of GetQuittingCount() action method:

string getActiveUsers = $"SELECT JsonData from [MetricCache] WHERE Type = 'get-quitting-count-job'";

An author has written raw SQL query to search for json collection in table MetricCache.
Problem is in my opinion that this table does not exists, Purpose of this table is unknown, maybe it was temporary table.