[BUG] Disallow loading rdf:langString literals with undefined language tag #808
Description
How: List of performed steps
Create an AspectModel that contains an rdf:langString value with an undefined language tag, e.g., :x samm:exampleValue "hello"^^rdf:langString (while the correct usage of rdf:langString would use the language tag syntax :x samm:exampleValue "hello"@en)
What: Actual result vs expected result
Expected: Loading and/or validation fails for this model
Actual: Model is loaded, missing language tag leads to unexpected behaviour (e.g., for sample JSON payload, "und" (as in "undefined") appears as the language key)