Fixes and guards for rendering ChatFeed and Card (#6177)

panel/chat/feed.py

@@ -277,7 +277,10 @@ def _get_model(
  self, doc: Document, root: Model | None = None,
  parent: Model | None = None, comm: Comm | None = None
  ) -> Model:
- return self._card._get_model(doc, root, parent, comm)
+ model = self._card._get_model(doc, root, parent, comm)
+ ref = (root or model).ref['id']
+ self._models[ref] = (model, parent)
+ return model
 
  def _cleanup(self, root: Model | None = None) -> None:
  self._card._cleanup(root)

panel/models/card.ts

@@ -12,8 +12,7 @@ export class CardView extends ColumnView {
  connect_signals(): void {
  super.connect_signals()
 
- const {active_header_background, children, collapsed, header_background, header_color, hide_header} = this.model.properties
- this.on_change(children, () => this.render())
+ const {active_header_background, collapsed, header_background, header_color, hide_header} = this.model.properties
  this.on_change(collapsed, () => this._collapse())
  this.on_change([header_color, hide_header], () => this.render())
 

panel/theme/base.py

@@ -246,6 +246,8 @@ def _apply_params(cls, viewable, mref, modifiers, document=None):
  # this may end up causing issues.
  from ..io.resources import CDN_DIST, patch_stylesheet
 
+ if mref not in viewable._models:
+ return
  model, _ = viewable._models[mref]
  params = {
  k: v for k, v in modifiers.items() if k != 'children' and