Improve error logging

src/main/kotlin/ch/memobase/rdf/RicoResource.kt

@@ -40,7 +40,12 @@ class RicoResource(val resource: Resource) {
         return try {
             resource.getProperty(RDF.type).resource
         } catch (ex: IllegalStateException) {
-            val message = "Resource without a ricoType: $resource." + ex.localizedMessage
+            val id = if (resource.isAnon) {
+                resource.id.labelString
+            } else {
+                resource.uri
+            }
+            val message = "Resource without a rdf:type: $id" + ex.localizedMessage
             log.error(message)
             throw InvalidInputException(message)
         }