[versions-check.csharp] Improve this script a bit (#10323)

* Pass -s to csharp to tell it the rest of the arguments are the script and its arguments.

    Fixes these warnings printed to the terminal:

        warning CS2002: Source file `7.0' specified multiple times
        warning CS2002: Source file `10.15' specified multiple times

* Add an exception handler and return 1 if there are any exceptions.

versions-check.csharp

@@ -1,4 +1,4 @@
-#!/usr/bin/env /Library/Frameworks/Mono.framework/Commands/csharp
+#!/usr/bin/env /Library/Frameworks/Mono.framework/Commands/csharp -s
 
 // this script is to make sure our versions.plist files are not out of date with our min/max supported OS versions.
 
@@ -7,35 +7,40 @@
 using System.IO;
 using System.Xml;
 
-var args = Environment.GetCommandLineArgs ();
-if (args.Length != 13 /* 2 default + 9 real */) {
+try {
+	var args = Environment.GetCommandLineArgs ();
+	var defaultArgumentsCount = 3;
+	var expectedArgumentCount = 11;
+	if (args.Length != defaultArgumentsCount + expectedArgumentCount) {
 		// first arg is "/Library/Frameworks/Mono.framework/Versions/4.8.0/lib/mono/4.5/csharp.exe"
 		// second arg the script itself
 		// then comes the ones we care about
 		Console.WriteLine ("Need 11 arguments, got {0}", args.Length - 2);
 		Environment.Exit (1);
 		return;
-}
+	}
 
-var plistPath = args [2];
-var iOSMin = args [3];
-var iOSMax = args [4];
-var tvOSMin = args [5];
-var tvOSMax = args [6];
-var watchOSMin = args [7];
-var watchOSMax = args [8];
-var macOSMin = args [9];
-var macOSMax = args [10];
-var MacCatalystMin = args [11];
-var MacCatalystMax = args [12];
+	args = args.Skip (defaultArgumentsCount).ToArray ();
 
-var doc = new System.Xml.XmlDocument ();
-doc.Load (plistPath);
+	var plistPath = args [0];
+	var iOSMin = args [1];
+	var iOSMax = args [2];
+	var tvOSMin = args [3];
+	var tvOSMax = args [4];
+	var watchOSMin = args [5];
+	var watchOSMax = args [6];
+	var macOSMin = args [7];
+	var macOSMax = args [8];
+	var MacCatalystMin = args [9];
+	var MacCatalystMax = args [10];
 
-var failed = false;
+	var doc = new System.Xml.XmlDocument ();
+	doc.Load (plistPath);
 
-var check = new Action<string, string, string> ((product, min, max) =>
-{
+	var failed = false;
+
+	var check = new Action<string, string, string> ((product, min, max) =>
+	{
 		var minVersion = Version.Parse (min);
 		var maxVersion = Version.Parse (max);
 		var foundMax = false;
@@ -69,12 +74,16 @@ var check = new Action<string, string, string> ((product, min, max) =>
 			Console.Error.WriteLine ($"Could not find the min {product} version {min} in {Path.GetFileName (plistPath)}.");
 			failed = true;
 		}
-});
+	});
 
-check ("iOS", iOSMin, iOSMax);
-check ("tvOS", tvOSMin, tvOSMax);
-check ("watchOS", watchOSMin, watchOSMax);
-check ("macOS", macOSMin, macOSMax);
-check ("MacCatalyst", MacCatalystMin, MacCatalystMax);
+	check ("iOS", iOSMin, iOSMax);
+	check ("tvOS", tvOSMin, tvOSMax);
+	check ("watchOS", watchOSMin, watchOSMax);
+	check ("macOS", macOSMin, macOSMax);
+	check ("MacCatalyst", MacCatalystMin, MacCatalystMax);
 
-Environment.Exit (failed ? 1 : 0);
+	Environment.Exit (failed ? 1 : 0);
+} catch (Exception e) {
+	Console.WriteLine (e);
+	Environment.Exit (1);
+}