SQL Server bit datatype fails (min, max, sum, stddev, variance)

[James-Livingston]

Describe the bug
Cannot analyze or test a table with a column of datatype bit.
The Metrics min, max, sum, stddev, and variance fail on columns with a bit datatype. It does seem un-necessary to call these functions on a bit datatype.

To Reproduce
Steps to reproduce the behavior:
Create a table with a bit column.
Run a test against it.

[James-Livingston]

metrics:
    - avg

If you use this metric on a table, it will fail on BIT datatypes. The expected behavior should be similar to VARCHAR, where the SQL for avg\min\max\etc.... are not generated for VARCHAR columns.