Fix aria-describedby in tooltip targets

docs/getting-started/changelog.md

@@ -13,6 +13,7 @@ _During the beta period, these restrictions may be relaxed in the event of a mis
 - Fixed a bug where `disabled` could be set when buttons are rendered as links
 - Fixed a bug where hoisted dropdowns would render in the wrong position when place inside an `sl-dialog`
 - Fixed a bug where boolean aria attributes didn't explicitly set `true|false` string values in the DOM
+- Fixed a bug where `aria-describedby` was never set on tooltip targets in `sl-tooltip`
 - Improved `sl-icon-button` accessibility by encouraging proper use of `label` and hiding the internal icon from screen readers
 - Improved `sl-dropdown` accessibility by attaching `aria-haspopup` and `aria-expanded` to the slotted trigger
 - Removed `console.log` from modal utility

src/components/tooltip/tooltip.tsx

@@ -202,8 +202,10 @@ export class Tooltip {
     const oldTarget = this.target;
     const newTarget = this.getTarget();
 
-    if (oldTarget && newTarget !== oldTarget) {
+    if (newTarget !== oldTarget) {
-      oldTarget.removeAttribute('aria-describedby');
+      if (oldTarget) {
+        oldTarget.removeAttribute('aria-describedby');
+      }
       newTarget.setAttribute('aria-describedby', this.componentId);
     }
   }
@@ -227,7 +229,7 @@ export class Tooltip {
   render() {
     return (
       <Host onMouseOver={this.handleMouseOver} onMouseOut={this.handleMouseOut}>
-        <slot aria-describedby={this.componentId} onSlotchange={this.handleSlotChange} />
+        <slot onSlotchange={this.handleSlotChange} />
 
         {!this.disabled && (
           <div ref={el => (this.tooltipPositioner = el)} class="tooltip-positioner">