The attempt of using a non-existing positional argument should be reported as a compile time error while at the moment it causes the following exception:

java.lang.IndexOutOfBoundsException: Error trying to access field at position 2
at org.drools.core.factmodel.ClassDefinition.getField(ClassDefinition.java:185)
at org.drools.compiler.rule.builder.PatternBuilder.processPositional(PatternBuilder.java:609)
at org.drools.compiler.rule.builder.PatternBuilder.processConstraintsAndBinds(PatternBuilder.java:518)