Call AllocHGlobal in the try/catch

src/LibVLCSharp/Shared/Helpers/MarshalExtensions.cs

@@ -127,9 +127,10 @@ namespace LibVLCSharp.Shared.Helpers
                 return IntPtr.Zero;
 
             var bytes = Encoding.UTF8.GetBytes(str);
-            var nativeString = Marshal.AllocHGlobal(bytes.Length + 1);
+            var nativeString = IntPtr.Zero;
             try
             {
+                nativeString = Marshal.AllocHGlobal(bytes.Length + 1);
                 Marshal.Copy(bytes, 0, nativeString, bytes.Length);
                 Marshal.WriteByte(nativeString, bytes.Length, 0);
             }

src/LibVLCSharp/Shared/Helpers/MarshalUtils.cs

@@ -154,9 +154,10 @@ namespace LibVLCSharp.Shared.Helpers
 
         static void UseStructurePointer<T>(T structure, Action<IntPtr> action)
         {
-            var structurePointer = Marshal.AllocHGlobal(Marshal.SizeOf(structure));
+            var structurePointer = IntPtr.Zero;
             try
             {
+                structurePointer = Marshal.AllocHGlobal(Marshal.SizeOf(structure));
                 Marshal.StructureToPtr(structure, structurePointer, false);
                 action(structurePointer);
             }