fix(chip): more value checking

fixing issues found in a later pass

Author: serifine

src/chip-input/ux-chip-input.ts

@@ -21,7 +21,7 @@ export class UxChipInput implements Themable {
   public value: any = undefined;
 
   @bindable({ defaultBindingMode: bindingMode.twoWay })
-  public chipArray: Array<any> = new Array<any>();
+  public chipArray: Array<string> = new Array<string>();
 
   public view: View;
   private textbox: HTMLInputElement;
@@ -97,14 +97,22 @@ export class UxChipInput implements Themable {
     }
 
     if (key === 37) {
-      if (this.chipArray.length) {
-        this.textbox.value = this.chipArray.pop().toString();
+      if (this.chipArray) {
+        const chip = this.chipArray.pop();
+
+        if (chip !== undefined) {
+          this.textbox.value = chip;
+        }
       }
     }
   }
 
   public addChip() {
     if (this.textbox.value.length) {
+      if (!this.chipArray) {
+        this.chipArray = new Array<string>();
+      }
+
       this.chipArray.push(this.textbox.value);
       this.textbox.value = '';
       this.chipsChanged();
@@ -135,21 +143,21 @@ export class UxChipInput implements Themable {
       seperator = this.separator;
     }
 
-    if (this.chipArray) {
-      this.value = this.chipArray.join(seperator);
-    }
+    this.value = this.chipArray.join(seperator);
   }
 
   public valueChanged() {
+    if (this.value === null) {
+      return;
+    }
+
     let seperator = ', ';
 
     if (this.separator) {
       seperator = this.separator;
     }
-    
-    if (this.value) {
-      this.chipArray = this.value.split(seperator);
-    }
+
+    this.chipArray = this.value.split(seperator);
   }
 
   public disabledChanged(newValue: any) {