fix(textinput): displaying empty input value if value is undefined or null (#936)

#935

src/TextArea/TextArea.svelte

@@ -85,7 +85,7 @@
       name="{name}"
       cols="{cols}"
       rows="{rows}"
-      value="{value}"
+      value="{value ?? ''}"
       placeholder="{placeholder}"
       class:bx--text-area="{true}"
       class:bx--text-area--light="{light}"

src/TextInput/PasswordInput.svelte

@@ -170,7 +170,7 @@
         name="{name}"
         placeholder="{placeholder}"
         type="{type}"
-        value="{value}"
+        value="{value ?? ''}"
         disabled="{disabled}"
         class:bx--text-input="{true}"
         class:bx--password-input="{true}"

src/TextInput/TextInput.svelte

@@ -163,7 +163,7 @@
         name="{name}"
         placeholder="{placeholder}"
         type="{type}"
-        value="{value}"
+        value="{value ?? ''}"
         required="{required}"
         readonly="{readonly}"
         class:bx--text-input="{true}"