Check "polar" keyword is set before and during `resolve`

[jmbhughes]

Is your feature request related to a problem? Please describe.
The polar keyword in the meta gets used but there is no sanity check for it.

Describe the solution you'd like
Check that it has a valid value at the start and that values propagate.

Describe alternatives you've considered
None

Additional context
This could cause annoying complications for other users if they don't realize it must be set.