Fix missing checks in execute and use match in loops

[pscott]

Fixes some missing checks in execute, update proposal, and min/max setters.
Also uses match in loops when possible.

Closes #501

[Orland0x]

we also need to update _get_cumulative_power in the space, still uses inefficient looping.

[pscott]

we also need to update _get_cumulative_power in the space, still uses inefficient looping.

yeah I thought I'd do it in another PR but you're right. Updated _get_cumulative_power and its function signature to use Span rather than Array

[Orland0x]

uTACK