fix(chip): correct broken variant type and restrict to union, reword

Author: damyanpetev

CHANGELOG.md

@@ -2,6 +2,12 @@
 
 All notable changes for each version of this project will be documented in this file.
 
+## 20.0.0
+
+### General
+- `IgxChip`
+    - **Behavioral Change** The `variant` is now strictly typed with the union of supported options and no longer accepts invalid values for the default state, provide no value (nullish) instead is needed.
+
 ## 19.2.0
 
 ### General

projects/igniteui-angular/src/lib/chips/chip.component.ts

@@ -32,6 +32,7 @@ export const IgxChipTypeVariant = {
     WARNING: 'warning',
     DANGER: 'danger'
 } as const;
+export type IgxChipTypeVariant = (typeof IgxChipTypeVariant)[keyof typeof IgxChipTypeVariant];
 
 export interface IBaseChipEventArgs extends IBaseEventArgs {
     originalEvent: IDragBaseEventArgs | IDropBaseEventArgs | KeyboardEvent | MouseEvent | TouchEvent;
@@ -93,15 +94,15 @@ export class IgxChipComponent implements OnInit, OnDestroy {
      *
      * @remarks
      * Allowed values are `primary`, `info`, `success`, `warning`, `danger`.
-     * Providing an invalid value won't change the chip.
+     * Providing no/nullish value leaves the chip in its default state.
      *
      * @example
      * ```html
-     * <igx-chip [variant]="success"></igx-chip>
+     * <igx-chip variant="success"></igx-chip>
      * ```
      */
     @Input()
-    public variant: string | typeof IgxChipTypeVariant;
+    public variant?: IgxChipTypeVariant | null;
     /**
      * Sets the value of `id` attribute. If not provided it will be automatically generated.
      *