Expands a (possibly level-named or level-length) numeric weight vector into a full vector over all group levels in factor order, validating that it references known levels, sums to zero and is not trivially zero.
resolve_contrast_weights(x, orig_levels)A numeric vector of length length(orig_levels) summing to zero.
Numeric weight vector, either named by group levels (missing levels are
filled with 0) or of length length(orig_levels) in factor order.
Character vector of the group factor levels (in order).