If an user import a mapping with a nonexistent type, no error is triggered. Everything seems to be okay.
But when actually using the mapping on a data import, the error message:
"[Error] Could not insert new record for object: Type must be specified" appears.
This error is misleading. I lost a lot of time thinking it was linked to the "type" argument in json parameters for entitySplitter.
In fact it was linked to the "type" in mapping settings.
It should be checked when importing mapping, and should be a fatal error preventing mapping to be imported.