Minimal sample to reproduce crash:

function noReturnDocTag() {
  const o = {};
  return { ...o };
}

Esdoc try to guess function return type when not @return tag found. When return type is Object, most times it can determine it's shape from AST. But when this object contains rest spread operator, it became compicated (for ex return { ...obj }, theorethically we can try track deeper and determine shape of obj, but for now we simple break guessing with *). In any case, this commit fixed crash with this case, because when AST node contain object with type SpreadProperty, it of course has no key.