ng-model pointing to an expression containing square brackets fail if a middle value is undefined

[gustavohenke]

If I have a ng-model pointing to an expression which contains square brackets, and a middle value is undefined, an error like the following will be thrown:

TypeError: Cannot set property 'foo' of undefined

Example code:

<input type="text" ng-model="foo.bar['baz']">
<input type="text" ng-model="foo['bar'].baz">

I have tested this in v1.2.16 and then in v1.2.19. Both have the same problem.
Reproducible plunk: http://plnkr.co/edit/NKgyYDkqjOugjbNjWnmA?p=preview

[mike-marcacci]

Hi there, just wondering if this could be bumped up from "inconvenience" severity. It's a total blocker for me on json-schema-form/angular-schema-form#43