Advanced Filter seems broken

[nickluger]

Describe the Bug

Was trying to write a PR for #6892, but it seems advanced filters are broken in the latest commit 99435b5.

EDIT: This might not affect the latest released version of Directus. Everything worked fine on our 9.0.0-rc.85 production version. But i cannot continue working on the PR without a fix.

To Reproduce

1. Run Directus locally
2. Use any advanced filter in the sidebar.
3. See this error

runtime-core.esm-bundler.js:218 Uncaught TypeError: Cannot read property '0' of undefined
    at addFilterForField (filter-sidebar-detail.vue:146)
    at callWithErrorHandling (runtime-core.esm-bundler.js:155)
    at callWithAsyncErrorHandling (runtime-core.esm-bundler.js:164)
    at emit (runtime-core.esm-bundler.js:993)
    at _createBlock.onClick._cache.<computed>._cache.<computed> (field-list-item.vue:5)
    at callWithErrorHandling (runtime-core.esm-bundler.js:155)
    at callWithAsyncErrorHandling (runtime-core.esm-bundler.js:164)
    at HTMLLIElement.invoker (runtime-dom.esm-bundler.js:349)

in

<FieldListItem key="status" field= {name: "Status", field: "status", key: "status", sort: 2} onAdd=fn<addFilterForField> > 
  at <VList> 
  at <TransitionGroup name="bounce" tag="div" > 
  at <TransitionBounce> 
  at <VMenu attached="" disabled=false > 
  at <BaseTransition mode="in-out" onBeforeEnter=fn<onBeforeEnter> onEnter=fn  ... > 
  at <Transition name="expand-transition" mode="in-out" onBeforeEnter=fn<beforeEnter>  ... > 
  at <TransitionExpand class="scroll-container" > 
  at <SidebarDetail badge=null icon="filter_list" title="Advanced Filter" > 
  at <FilterSidebarDetail modelValue= [{…}] onUpdate:modelValue=fn collection="review"  ... > 
  at <Sidebar> 
  at <VItemGroup modelValue= ["Advanced Filter"] onUpdate:modelValue=fn class="sidebar-detail-group"  ... > 
  at <SidebarDetailGroup sidebar-open=true > 
  at <PrivateView key=1 title="Reviews" singleton=false > 
  at <AsyncComponentWrapper key=1 title="Reviews" singleton=false > 
  at <CollectionsCollection collection="review" bookmark=null singleton=false > 
  at <CollectionOrItem collection="review" bookmark=undefined onVnodeUnmounted=fn<onVnodeUnmounted>  ... > 
  at <RouterView> 
  at <RouterPassthrough onVnodeUnmounted=fn<onVnodeUnmounted> ref=Ref< <!----> > > 
  at <RouterView> 
  at <RouterPassthrough onVnodeUnmounted=fn<onVnodeUnmounted> ref=Ref< <!----> > > 
  at <RouterView key=1 > 
  at <App>

What version of Directus are you using?

Commit 99435b5

What version of Node.js are you using?

=14

What database are you using?

postgres:12.5

What browser are you using?

Chrome

What operating system are you using?

macOS

How are you deploying Directus?

running locally