[c] Improve error handling when marshaling classes.
[c] Improve error handling when marshaling classes.

mono/Embeddinator-4000,mono/Embeddinator-4000,mono/Embeddinator-4000,mono/Embeddinator-4000,jonathanpeppers/Embeddinator-4000,mono/Embeddinator-4000,jonathanpeppers/Embeddinator-4000,mono/Embeddinator-4000,jonathanpeppers/Embeddinator-4000,jonathanpeppers/Embeddinator-4000,mono/Embeddinator-4000,jonathanpeppers/Embeddinator-4000,jonathanpeppers/Embeddinator-4000,jonathanpeppers/Embeddinator-4000