nullability fixes

Author: moljac

tests/allpackages/TestAllIndividualPackages.cs

@@ -182,9 +182,10 @@ async Task TestAllPackages (string template, bool isGps)
 
 		XmlNodeList nl = xd.SelectNodes("//*[starts-with(name(), 'TargetFramework')]");
 
-		foreach (XmlNode node in nl) 
-		{
-			node.InnerText = $"{net_version}-android";
+		if (nl is not null) {
+			foreach (XmlNode node in nl) {
+				node.InnerText = $"{net_version}-android";
+			}
 		}
 		xd.Save(proj_file);
 

tests/extended/TestAllIndividualPackages.cs

@@ -1,4 +1,5 @@
 using System.Text;
+using System.Xml;
 using CliWrap;
 using CliWrap.Buffered;
 using NUnit.Framework;
@@ -97,11 +98,12 @@ async Task TestPackage (string id, string version, string template)
 			XmlDocument xd = new ();
 			xd.Load (proj_file);
 
-			XmlNodeList nl = xd.SelectNodes("//*[starts-with(name(), 'TargetFramework')]");
+			XmlNodeList? nl = xd.SelectNodes("//*[starts-with(name(), 'TargetFramework')]");
 
-			foreach (XmlNode node in nl) 
-			{
-				node.InnerText = $"{net_version}-android";
+			if (nl is not null) {
+				foreach (XmlNode node in nl) {
+					node.InnerText = $"{net_version}-android";
+				}
 			}
 			xd.Save(proj_file);