As discussed with @westey-m offline... We currently wrap any exceptions coming out of mapping (serialization/deserialization) with VectorStoreRecordMappingException. Especially now that we've removed custom mapping, any exceptions coming out of mapping are either errors in connector code, or in user code (e.g. they're passing int via Dictionary<string, object?> where the property is configured as string), or in connector code. In general, such coding errors aren't meant to be caught and handle (like I/O errors), but rather the code should be fixed.

So I think it's fine to just have the mapping code throw InvalidCastException, ideally with an informative message about which property got a mismatched value.

Not strictly speaking necessary for Build, but I'd do this anyway as it's pretty simple and would simplify the code etc.