Converts a flexible input into a non-empty array where the call site expects at least one value, so the expectation
is stated once and broken inputs fail at the boundary rather than downstream. The result type guarantees a first
element, letting callers read it without a presence check.
Reduces a Some value to the values it must hold.
Converts a flexible input into a non-empty array where the call site expects at least one value, so the expectation is stated once and broken inputs fail at the boundary rather than downstream. The result type guarantees a first element, letting callers read it without a presence check.