Fix null! and empty catch

Author: simonrozsival

src/Microsoft.Android.Sdk.TrimmableTypeMap/Generator/ModelBuilder.cs

@@ -50,7 +50,7 @@ public static TypeMapAssemblyData Build (IReadOnlyList<JavaPeerInfo> peers, stri
 		// Invoker types are NOT emitted as separate proxies or TypeMap entries —
 		// they only appear as a TypeRef in the interface proxy's get_InvokerType property.
 		var invokerTypeNames = new HashSet<string> (
-			peers.Where (p => p.InvokerTypeName != null).Select (p => p.InvokerTypeName!),
+			peers.Where (p => p.InvokerTypeName != null).Select (p => p.InvokerTypeName ?? ""),
 			StringComparer.Ordinal);
 
 		// Group non-invoker peers by JNI name to detect aliases (multiple .NET types → same Java class).

tests/Microsoft.Android.Sdk.TrimmableTypeMap.Tests/Generator/FixtureTestBase.cs

@@ -137,6 +137,6 @@ private protected static string CreateTempDir ()
 	private protected static void DeleteTempDir (string dir)
 	{
 		if (Directory.Exists (dir))
-			try { Directory.Delete (dir, true); } catch { }
+			try { Directory.Delete (dir, true); } catch (IOException) { }
 	}
 }

tests/Microsoft.Android.Sdk.TrimmableTypeMap.Tests/Generator/TypeMapModelBuilderTests.cs

@@ -788,7 +788,8 @@ public void Fixture_MainActivity_UcoMethods ()
 		{
 			var peer = FindFixtureByJavaName ("my/app/MainActivity");
 			var model = BuildModel (new [] { peer }, "TypeMap");
-			var proxy = FindProxy (model, "MyApp_MainActivity_Proxy")!;
+			var proxy = FindProxy (model, "MyApp_MainActivity_Proxy");
+			Assert.NotNull (proxy);
 
 			var nonCtorMethods = peer.MarshalMethods.Where (m => !m.IsConstructor).ToList ();
 			Assert.Equal (nonCtorMethods.Count, proxy.UcoMethods.Count);