Optional Chaining in delete statement removes delete statement

[goresynopsys]

We discovered a discrepancy between transpiled and untranspiled Javascript which was introduced when upgrading ember-cli-babel from 7.26.4 to 7.26.11. Nested if statements get transpiled incorrectly (removing the nested if):

(source)

let isBlogPost = filter.key.includes('post');
let strippedKey = filter.key.replace(FILTER_KEY_REGEX, '');
if (filterQueryParams?.post) {
  if (isBlogPost) {
    delete filterQueryParams['post']['taxonomy']?.['taxonomy-type'][strippedKey];
    if (filterOption?.taxonomyType) {
      delete filterQueryParams['post']['taxonomy']?.['taxonomy-type'][filterOption.taxonomyType];
    }
  } else {
    delete filterQueryParams['post'][strippedKey];
  }
}

(transpiled)

let {filter: t, filterQueryParams: i, filterOption: r, selectedValues: n, params: s} = e
			  , a = t.key.includes("post")
			  , o = t.key.replace(A, "")
			i?.post && (a ? (i.post.taxonomy?.["taxonomy-type"][o],
			r?.taxonomyType && i.post.taxonomy?.["taxonomy-type"][r.taxonomyType]) : delete i.post[o])

Our interim fix involved refactoring the duplicated, target key to delete into a new variable, taxonomyType, as follows:

const FILTER_KEY_REGEX = /^filter_/;
let isBlogPost = filter.key.includes('post');
let strippedKey = filter.key.replace(FILTER_KEY_REGEX, '');
if (filterQueryParams?.post) {
  let taxonomyType = filterQueryParams.post.taxonomy?.['taxonomy-type'];
  if (isBlogPost) {
    delete taxonomyType[strippedKey];
    if (filterOption?.taxonomyType) {
      delete taxonomyType[filterOption.taxonomyType];
    }
  } else {
    delete filterQueryParams['post'][strippedKey];
  }
}

[goresynopsys]

Update: this may have more to do with optional chaining within a delete call than the if statements...

[RobbieTheWagner]

We're also seeing this bug with current_page: pagination.self?.number ?? 0, ember-cli-babel converts that to current_page: undefined ?? 0,