NPE when an unknown field is specified in the pull pattern

[xfthhxk]

java.lang.NullPointerException: Cannot invoke "java.lang.Number.intValue()" because the return value of "clojure.lang.ISeq.first()" is null
 at clojure.lang.Numbers.int_array (Numbers.java:1300)
    conceptual.core$normalize_ids.invokeStatic (core.clj:195)
    conceptual.core$normalize_ids.invoke (core.clj:187)
    conceptual.core$project_map.invokeStatic (core.clj:445)
    conceptual.core$project_map.invoke (core.clj:441)
    conceptual.core$project_map.invokeStatic (core.clj:443)
    conceptual.core$project_map.invoke (core.clj:441)
    conceptual.alpha.pull$pull.invokeStatic (pull.clj:279)