ENT-13824: Error on rval call that are not builtin-functions inside vars-promise

Signed-off-by: Simon Halvorsen <simon.halvorsen@northern.tech>

Author: SimonThalvorsen

src/cfengine_cli/lint.py

@@ -515,6 +515,14 @@ def _lint_node(node: Node, policy_file: PolicyFile, state: State) -> int:
                 f"Error: Call to unknown function / bundle / body '{name}' {location}"
             )
             return 1
+        if state.strict and (
+            name not in BUILTIN_FUNCTIONS and state.promise_type == "vars"
+        ):
+            _highlight_range(node, lines)
+            print(
+                f"Error: Call to unknown function '{name}' inside 'vars'-promise {location}"
+            )
+            return 1
     return 0