Report an out-of-range number for an option as a usage error [patch]

README.md

@@ -164,8 +164,8 @@ way out. A user flicking a toggle back and forth produces one write, not one per
 ```
 
 They appear in `--help` in registration order, between the tray switches and `--for`. A value handler
-that throws `FormatException` or `ArgumentException` turns its message into the usage error, and the
-tool exits 2 without starting.
+that throws `FormatException`, `ArgumentException` or `OverflowException` (what `int.Parse` throws for a
+number out of range) turns its message into the usage error, and the tool exits 2 without starting.
 
 ### Adding rows to `--status`
 

TrayApp.Test/TrayAppBuilderTests.cs

@@ -161,7 +161,7 @@
 	}
 
 	[TestMethod]
 	public void Preferences_WithTheLongestDebounce_IsAcceptedAndATimerTakesIt()
 	{
 		InMemoryPersistenceProvider<string> provider = new();
 		TrayAppDefinition app = TrayAppBuilder.Create("demo")
@@ -303,6 +303,21 @@
 		Assert.AreEqual("'lots' is not a number.", error);
 	}
 
+	[TestMethod]
+	public void TryApplyOptions_WhenAHandlerParsesAnOutOfRangeNumber_ReportsItAsAUsageError()
+	{
+		// int.Parse throws OverflowException, not FormatException, for a number too big for an int, and
+		// that used to escape as an unhandled exception (#69).
+		TrayAppDefinition app = TrayAppBuilder.Create("demo")
+			.Option(["--count"], "n", "How many.", value => _ = int.Parse(value, System.Globalization.CultureInfo.InvariantCulture))
+			.Build();
+
+		Assert.IsTrue(CommandLineParser.TryParse(["--count", "99999999999"], app.Options, out CommandLineOptions options, out _));
+		Assert.IsFalse(TrayAppBuilder.TryApplyOptions(options, out string error));
+		string expected = Assert.ThrowsExactly<OverflowException>(() => int.Parse("99999999999", System.Globalization.CultureInfo.InvariantCulture)).Message;
+		Assert.AreEqual(expected, error);
+	}
+
 	[TestMethod]
 	public async Task RunAsync_WithHelp_PrintsUsageAndSucceeds()
 	{

TrayApp/TrayAppBuilder.cs

@@ -559,7 +559,7 @@ internal static bool TryApplyOptions(CommandLineOptions options, out string erro
 			{
 				match.Option.Apply(match.Value);
 			}
-			catch (Exception ex) when (ex is FormatException or ArgumentException)
+			catch (Exception ex) when (ex is FormatException or ArgumentException or OverflowException)
 			{
 				error = ex.Message;
 				return false;