Guard against null passwords 1/2

Author: Nuklon

src/Wpf.Ui/Controls/PasswordBox/PasswordBox.cs

@@ -77,7 +77,7 @@ public PasswordBox()
     /// <summary>
     /// Gets or sets the actual password (not asterisks).
     /// </summary>
-    public string Password
+    public string? Password
     {
         get => (string)GetValue(PasswordProperty);
         set => SetValue(PasswordProperty, value);
@@ -102,7 +102,7 @@ public bool IsPasswordRevealed
     }
 
     /// <summary>
-    /// Gets or sets whether the password reveal button is enabled.
+    /// Gets or sets a value indicating whether gets or sets whether the password reveal button is enabled.
     /// </summary>
     public bool RevealButtonEnabled
     {
@@ -147,15 +147,15 @@ protected virtual void OnPasswordCharChanged()
             return;
         }
 
-        UpdateWithLock(() => SetCurrentValue(TextProperty, new string(PasswordChar, Password.Length)));
+        UpdateWithLock(() => SetCurrentValue(TextProperty, new string(PasswordChar, Password?.Length ?? 0)));
     }
 
     /// <summary>
     /// Called when the <see cref="IsPasswordRevealed"/> property changes.
     /// </summary>
     protected virtual void OnIsPasswordRevealedChanged()
     {
-        UpdateWithLock(() => SetCurrentValue(TextProperty, IsPasswordRevealed ? Password : new string(PasswordChar, Password.Length)));
+        UpdateWithLock(() => SetCurrentValue(TextProperty, IsPasswordRevealed ? Password : new string(PasswordChar, Password?.Length ?? 0)));
     }
 
     /// <inheritdoc/>
@@ -231,7 +231,7 @@ private void HandleHiddenModeUpdate(bool isTriggeredByTextInput)
 
         UpdateWithLock(() =>
         {
-            SetCurrentValue(TextProperty, new string(PasswordChar, newPassword.Length));
+            SetCurrentValue(TextProperty, new string(PasswordChar, newPassword?.Length ?? 0));
             SetCurrentValue(PasswordProperty, newPassword);
             CaretIndex = caretIndex;
             RaisePasswordChangedEvent();