TypeError in model.filter watch if not object

[Decipher]

Describe the bug
The DruxtView model.filter expects to and from to be objects, so if the are not it causes an error:

client.js?06a0:103 TypeError: Cannot convert undefined or null to object
    at Function.entries (<anonymous>)
    at _callee3$ (DruxtView.vue?889b:300:1)
    at tryCatch (runtime.js?96cf:63:1)
    at Generator.invoke [as _invoke] (runtime.js?96cf:294:1)
    at Generator.eval [as next] (runtime.js?96cf:119:1)
    at asyncGeneratorStep (asyncToGenerator.js?1da1:3:1)
    at _next (asyncToGenerator.js?1da1:25:1)
    at eval (asyncToGenerator.js?1da1:32:1)
    at new Promise (<anonymous>)
    at eval (asyncToGenerator.js?1da1:21:1)

To Reproduce
...

Expected behavior
Don't run Object functions if they aren't objects.

Media
N/A

Your Environment (please complete the following information):
N/A

Additional context
https://github.com/druxt/druxt.js/blob/develop/packages/views/src/components/DruxtView.vue#L300