refactor(alert, autocomplete, combobox, dialog, dropdown, input-date-…

…picker, modal, notice, popover, sheet, tooltip): avoid clearing `transitionEl` ref nodes (#11497)

**Related Issue:** #11093

## Summary

Updates transition element `ref` callbacks to avoid clearing the
reference. This should preserve the context of existing ref logic.

packages/calcite-components/src/components/alert/alert.tsx

@@ -326,6 +326,10 @@ export class Alert extends LitElement implements OpenCloseComponent {
   }
 
   private setTransitionEl(el: HTMLDivElement): void {
+    if (!el) {
+      return;
+    }
+
     this.transitionEl = el;
   }
 

packages/calcite-components/src/components/autocomplete/autocomplete.tsx

@@ -756,6 +756,10 @@ export class Autocomplete
   }
 
   private setTransitionEl(el: HTMLDivElement): void {
+    if (!el) {
+      return;
+    }
+
     this.transitionEl = el;
   }
 

packages/calcite-components/src/components/combobox/combobox.tsx

@@ -1070,9 +1070,11 @@ export class Combobox
   }
 
   private setContainerEl(el: HTMLDivElement): void {
-    if (el) {
-      this.resizeObserver?.observe(el);
+    if (!el) {
+      return;
     }
+
+    this.resizeObserver?.observe(el);
     this.listContainerEl = el;
     this.transitionEl = el;
   }

packages/calcite-components/src/components/dialog/dialog.tsx

@@ -678,6 +678,10 @@ export class Dialog extends LitElement implements OpenCloseComponent {
   }
 
   private setTransitionEl(el: HTMLDivElement): void {
+    if (!el) {
+      return;
+    }
+
     this.transitionEl = el;
     this.setupInteractions();
   }

packages/calcite-components/src/components/dropdown/dropdown.tsx

@@ -493,9 +493,11 @@ export class Dropdown
   }
 
   private setScrollerAndTransitionEl(el: HTMLDivElement): void {
-    if (el) {
-      this.resizeObserver?.observe(el);
+    if (!el) {
+      return;
     }
+
+    this.resizeObserver?.observe(el);
     this.scrollerEl = el;
     this.transitionEl = el;
   }

packages/calcite-components/src/components/input-date-picker/input-date-picker.tsx

@@ -679,6 +679,10 @@ export class InputDatePicker
   }
 
   private setTransitionEl(el: HTMLDivElement): void {
+    if (!el) {
+      return;
+    }
+
     this.transitionEl = el;
   }
 

packages/calcite-components/src/components/modal/modal.tsx

@@ -359,6 +359,10 @@ export class Modal extends LitElement implements OpenCloseComponent {
   }
 
   private setTransitionEl(el: HTMLDivElement): void {
+    if (!el) {
+      return;
+    }
+
     this.transitionEl = el;
   }
 

packages/calcite-components/src/components/notice/notice.tsx

@@ -185,6 +185,10 @@ export class Notice extends LitElement implements OpenCloseComponent {
   }
 
   private setTransitionEl(el: HTMLElement): void {
+    if (!el) {
+      return;
+    }
+
     this.transitionEl = el;
   }
 

packages/calcite-components/src/components/popover/popover.tsx

@@ -356,6 +356,10 @@ export class Popover extends LitElement implements FloatingUIComponent, OpenClos
   }
 
   private setTransitionEl(el: HTMLDivElement): void {
+    if (!el) {
+      return;
+    }
+
     this.transitionEl = el;
   }
 

packages/calcite-components/src/components/sheet/sheet.tsx

@@ -532,6 +532,10 @@ export class Sheet extends LitElement implements OpenCloseComponent {
   }
 
   private setTransitionEl(el: HTMLDivElement): void {
+    if (!el) {
+      return;
+    }
+
     this.transitionEl = el;
   }
 

packages/calcite-components/src/components/tooltip/tooltip.tsx

@@ -246,6 +246,10 @@ export class Tooltip extends LitElement implements FloatingUIComponent, OpenClos
   }
 
   private setTransitionEl(el: HTMLDivElement): void {
+    if (!el) {
+      return;
+    }
+
     this.transitionEl = el;
   }