Errors with different path got overwritten

When there are errors of more than one different paths in ajv error list, the `helpers.makeTree` function will overwrite the previous errors in the path with the new one in the reduce function:
```javascript
paths &&
paths.reduce((obj, path, i) => {
obj.children[path] = obj.children[path] || { children: {}, errors: [] };
if (i === paths.length - 1) {
obj.children[path].errors.push(ajvError);
}
return obj.children[path];
}, root);
```
Is this an intended design?

Locate the helpers.makeTree function and trace the reduce callback shown in the issue, then reproduce the behavior with AJV errors from different paths. Confirm with the maintainer whether errors from each path should be retained; the work is done when that behavior is decided and covered by a regression test.

Written by the indexing model from the issue text.