Improve error handling when searching for type maps via reflection.

src/Generator/Types/TypeMap.cs

@@ -140,8 +140,16 @@ namespace CppSharp.Types
 
             foreach (var assembly in loadedAssemblies)
             {
-                var types = assembly.FindDerivedTypes(typeof(TypeMap));
+                try
-                SetupTypeMaps(types, generatorKind);
+                {
+                    var types = assembly.FindDerivedTypes(typeof(TypeMap));
+                    SetupTypeMaps(types, generatorKind);
+                }
+                catch (System.Reflection.ReflectionTypeLoadException ex)
+                {
+                    Diagnostics.Error("Error loading type maps from assembly '{0}': {1}",
+                        assembly.GetName().Name, ex.Message);
+                }
             }
         }