Improve error handling when searching for type maps via reflection.

src/Generator/Types/TypeMap.cs

@@ -139,10 +139,18 @@ namespace CppSharp.Types
             var loadedAssemblies = AppDomain.CurrentDomain.GetAssemblies();
 
             foreach (var assembly in loadedAssemblies)
+            {
+                try
                 {
                     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);
+                }
+            }
         }
 
         private void SetupTypeMaps(IEnumerable<System.Type> types, GeneratorKind generatorKind)