bug: absence of requires_last_push_approval not handled correctly

[AlexanderLanin]

When a repo rulesets required_pull_request does not have requires_last_push_approval there is no validation error or planning error. When applied there is a super cryptic error message: Error for key require_last_push_approval: 'requires_last_push_approval'

Secondary bug which makes this one hard to spot: requires_last_push_approval does not show up in plan/diff outputs.

Example where error was encountered, note that the second diff does not show requires_last_push_approval was removed.
eclipse-score/.eclipsefdn#190

Example where the error was (hopefully) fixed (not merged yet), and again no diff output: eclipse-score/.eclipsefdn#200

[netomi]

the canonical way would be to define the ruleset like that:

local default_review_rule = orgs.newPullRequest() {
  # dismiss approved reviews automatically when a new commit is pushed
  dismisses_stale_reviews: true,

  # The number of approvals required before a pull request can be merged [0,10]
  required_approving_review_count: 1,

  # require an approved review in pull requests including files with a designated code owner
  requires_code_owner_review: true,

  # TODO: the most recent push must be approved by someone other than the person who pushed it
  # requires_last_push_approval: true,
};

you take use the template function to make sure all values are defined and then override the ones that you wanna change.
If you would run an import, that is what otterdog would generate.

The other solution with the :+ is also fine.

The referenced fix should make this also less error-prone.

[netomi]

should be fixed by #675