diff --git a/biscuit-core/src/main/java/org/eclipse/biscuit/datalog/Rule.java b/biscuit-core/src/main/java/org/eclipse/biscuit/datalog/Rule.java
index e7457720..6aa3d584 100644
--- a/biscuit-core/src/main/java/org/eclipse/biscuit/datalog/Rule.java
+++ b/biscuit-core/src/main/java/org/eclipse/biscuit/datalog/Rule.java
@@ -72,10 +72,10 @@ public Stream<Result<Pair<Origin, Fact>, Error>> apply(
                 }
                 // continue evaluating if true
               } else {
-                return Stream.empty();
+                return Stream.of(Result.err(new Error.InvalidType()));
               }
             } catch (Error error) {
-              return Stream.empty();
+              return Stream.of(Result.err(error));
             }
           }