use public method for validity

src/components/checkbox/checkbox.ts

@@ -81,7 +81,7 @@ export default class SlCheckbox extends ShoelaceElement implements ShoelaceFormC
   @defaultValue('checked') defaultChecked = false;
 
   firstUpdated() {
-    this.invalid = !this.input.checkValidity();
+    this.invalid = !this.checkValidity();
   }
 
   private handleClick() {
@@ -108,7 +108,7 @@ export default class SlCheckbox extends ShoelaceElement implements ShoelaceFormC
   handleDisabledChange() {
     // Disabled form controls are always valid, so we need to recheck validity when the state changes
     this.input.disabled = this.disabled;
-    this.invalid = !this.input.checkValidity();
+    this.invalid = !this.checkValidity();
   }
 
   @watch('checked', { waitUntilFirstUpdate: true })
@@ -116,7 +116,7 @@ export default class SlCheckbox extends ShoelaceElement implements ShoelaceFormC
   handleStateChange() {
     this.input.checked = this.checked; // force a sync update
     this.input.indeterminate = this.indeterminate; // force a sync update
-    this.invalid = !this.input.checkValidity();
+    this.invalid = !this.checkValidity();
   }
 
   /** Simulates a click on the checkbox. */
@@ -150,7 +150,7 @@ export default class SlCheckbox extends ShoelaceElement implements ShoelaceFormC
    */
   setCustomValidity(message: string) {
     this.input.setCustomValidity(message);
-    this.invalid = !this.input.checkValidity();
+    this.invalid = !this.checkValidity();
   }
 
   render() {

src/components/input/input.ts

@@ -220,7 +220,7 @@ export default class SlInput extends ShoelaceElement implements ShoelaceFormCont
   }
 
   firstUpdated() {
-    this.invalid = !this.input.checkValidity();
+    this.invalid = !this.checkValidity();
   }
 
   private handleBlur() {
@@ -285,7 +285,7 @@ export default class SlInput extends ShoelaceElement implements ShoelaceFormCont
   handleDisabledChange() {
     // Disabled form controls are always valid, so we need to recheck validity when the state changes
     this.input.disabled = this.disabled;
-    this.invalid = !this.input.checkValidity();
+    this.invalid = !this.checkValidity();
   }
 
   @watch('step', { waitUntilFirstUpdate: true })
@@ -293,13 +293,13 @@ export default class SlInput extends ShoelaceElement implements ShoelaceFormCont
     // If step changes, the value may become invalid so we need to recheck after the update. We set the new step
     // imperatively so we don't have to wait for the next render to report the updated validity.
     this.input.step = String(this.step);
-    this.invalid = !this.input.checkValidity();
+    this.invalid = !this.checkValidity();
   }
 
   @watch('value', { waitUntilFirstUpdate: true })
   handleValueChange() {
     this.input.value = this.value; // force a sync update
-    this.invalid = !this.input.checkValidity();
+    this.invalid = !this.checkValidity();
   }
 
   /** Sets focus on the input. */
@@ -377,7 +377,7 @@ export default class SlInput extends ShoelaceElement implements ShoelaceFormCont
   /** Sets a custom validation message. If `message` is not empty, the field will be considered invalid. */
   setCustomValidity(message: string) {
     this.input.setCustomValidity(message);
-    this.invalid = !this.input.checkValidity();
+    this.invalid = !this.checkValidity();
   }
 
   render() {

src/components/range/range.ts

@@ -175,7 +175,7 @@ export default class SlRange extends ShoelaceElement implements ShoelaceFormCont
 
   @watch('value', { waitUntilFirstUpdate: true })
   handleValueChange() {
-    this.invalid = !this.input.checkValidity();
+    this.invalid = !this.checkValidity();
 
     // The value may have constraints, so we set the native control's value and sync it back to ensure it adhere's to
     // min, max, and step properly
@@ -189,7 +189,7 @@ export default class SlRange extends ShoelaceElement implements ShoelaceFormCont
   handleDisabledChange() {
     // Disabled form controls are always valid, so we need to recheck validity when the state changes
     this.input.disabled = this.disabled;
-    this.invalid = !this.input.checkValidity();
+    this.invalid = !this.checkValidity();
   }
 
   @watch('hasTooltip', { waitUntilFirstUpdate: true })
@@ -242,7 +242,7 @@ export default class SlRange extends ShoelaceElement implements ShoelaceFormCont
   /** Sets a custom validation message. If `message` is not empty, the field will be considered invalid. */
   setCustomValidity(message: string) {
     this.input.setCustomValidity(message);
-    this.invalid = !this.input.checkValidity();
+    this.invalid = !this.checkValidity();
   }
 
   render() {

src/components/switch/switch.ts

@@ -72,7 +72,7 @@ export default class SlSwitch extends ShoelaceElement implements ShoelaceFormCon
   @defaultValue('checked') defaultChecked = false;
 
   firstUpdated() {
-    this.invalid = !this.input.checkValidity();
+    this.invalid = !this.checkValidity();
   }
 
   private handleBlur() {
@@ -113,14 +113,14 @@ export default class SlSwitch extends ShoelaceElement implements ShoelaceFormCon
   @watch('checked', { waitUntilFirstUpdate: true })
   handleCheckedChange() {
     this.input.checked = this.checked; // force a sync update
-    this.invalid = !this.input.checkValidity();
+    this.invalid = !this.checkValidity();
   }
 
   @watch('disabled', { waitUntilFirstUpdate: true })
   handleDisabledChange() {
     // Disabled form controls are always valid, so we need to recheck validity when the state changes
     this.input.disabled = this.disabled;
-    this.invalid = !this.input.checkValidity();
+    this.invalid = !this.checkValidity();
   }
 
   /** Simulates a click on the switch. */
@@ -151,7 +151,7 @@ export default class SlSwitch extends ShoelaceElement implements ShoelaceFormCon
   /** Sets a custom validation message. If `message` is not empty, the field will be considered invalid. */
   setCustomValidity(message: string) {
     this.input.setCustomValidity(message);
-    this.invalid = !this.input.checkValidity();
+    this.invalid = !this.checkValidity();
   }
 
   render() {

src/components/textarea/textarea.ts

@@ -139,7 +139,7 @@ export default class SlTextarea extends ShoelaceElement implements ShoelaceFormC
   }
 
   firstUpdated() {
-    this.invalid = !this.input.checkValidity();
+    this.invalid = !this.checkValidity();
   }
 
   disconnectedCallback() {
@@ -181,7 +181,7 @@ export default class SlTextarea extends ShoelaceElement implements ShoelaceFormC
   handleDisabledChange() {
     // Disabled form controls are always valid, so we need to recheck validity when the state changes
     this.input.disabled = this.disabled;
-    this.invalid = !this.input.checkValidity();
+    this.invalid = !this.checkValidity();
   }
 
   @watch('rows', { waitUntilFirstUpdate: true })
@@ -192,7 +192,7 @@ export default class SlTextarea extends ShoelaceElement implements ShoelaceFormC
   @watch('value', { waitUntilFirstUpdate: true })
   handleValueChange() {
     this.input.value = this.value; // force a sync update
-    this.invalid = !this.input.checkValidity();
+    this.invalid = !this.checkValidity();
     this.updateComplete.then(() => this.setTextareaHeight());
   }
 
@@ -267,7 +267,7 @@ export default class SlTextarea extends ShoelaceElement implements ShoelaceFormC
   /** Sets a custom validation message. If `message` is not empty, the field will be considered invalid. */
   setCustomValidity(message: string) {
     this.input.setCustomValidity(message);
-    this.invalid = !this.input.checkValidity();
+    this.invalid = !this.checkValidity();
   }
 
   render() {