Refuse a blank NoteName in the Note constructor [patch]

Keybinding.Test/BlankNoteNameTests.cs

@@ -0,0 +1,34 @@
+// Copyright (c) 2023-2026 ktsu-dev contributors
+
+namespace ktsu.Keybinding.Test;
+
+using ktsu.Keybinding.Core.Models;
+
+[TestClass]
+public class BlankNoteNameTests
+{
+	[TestMethod]
+	[DataRow("")]
+	[DataRow(" ")]
+	[DataRow("\t")]
+	public void NoteFromBlankNoteName_ThrowsArgumentException(string key)
+	{
+		// The string constructor already refused a blank key; the NoteName one built an empty note that
+		// displayed as "Ctrl+", executed, and was then dropped when the profile was loaded again (#212).
+		NoteName name = NoteName.Create(key);
+		ArgumentException exception = Assert.ThrowsExactly<ArgumentException>(() => new Note(name));
+		Assert.AreEqual("key", exception.ParamName);
+		Assert.StartsWith("Key cannot be null or whitespace", exception.Message);
+	}
+
+	[TestMethod]
+	[DataRow("")]
+	[DataRow(" ")]
+	[DataRow("\t")]
+	public void NoteFromBlankString_ThrowsTheSameArgumentException(string key)
+	{
+		ArgumentException exception = Assert.ThrowsExactly<ArgumentException>(() => new Note(key));
+		Assert.AreEqual("key", exception.ParamName);
+		Assert.StartsWith("Key cannot be null or whitespace", exception.Message);
+	}
+}

Keybinding/Models/MusicalTypes.cs

@@ -19,6 +19,11 @@
 	public Note(NoteName key)
 	{
 		Ensure.NotNull(key);
+		if (string.IsNullOrWhiteSpace(key.ToString()))
+		{
+			throw new ArgumentException("Key cannot be null or whitespace", nameof(key));
+		}
+
 		string canonical = NormalizeKey(key.ToString());
 		Key = canonical == key.ToString() ? key : NoteName.Create(canonical);
 	}
@@ -64,7 +69,7 @@
 	/// </summary>
 	/// <param name="key">An uppercase key name</param>
 	/// <returns>The canonical key name</returns>
 	private static string CanonicalizeKey(string key)
 	{
 		if (key.Length == 2 && key[0] == 'D' && key[1] is >= '0' and <= '9')
 		{