Check for component before saving, fallback to full form field name

[tiller1010]

Closes #10188

Summary

Prevents Call to a member function setCastedField() on null error when using dot syntax for has_many components. This does not save has_many components by itself.

Additional notes

We have custom code that handles the saving of has_many components with dot syntax. This change breaks that functionality. This simply checks for a valid component before calling setCastedField. If the component does not exist, this will fallback to the original setCastedField procedure.

[GuySartorelli]

Nice. This effectively reverts back to the old behaviour it no component could be found - which a) avoids the null pointer exception this is meant to resolve, and b) allows for custom logic to choose what to do with the data in this situation where a component hasn't yet been created.