fixup: move conditional validation to decorator

src/semeio/forward_models/__init__.py

@@ -1,4 +1,4 @@
-from typing import Optional
+from typing import Callable, Optional
 
 from ert import (
     ForwardModelStepDocumentation,
@@ -11,6 +11,16 @@
 from .scripts.design_kw import design_kw as DesignKWScript
 
 
+def validation_enabled(validation_func: Callable) -> Callable[..., None]:
+    def wrapper(
+        self: ForwardModelStepPlugin, fm_step_json: ForwardModelStepJSON
+    ) -> None:
+        if self.private_args.get("<VALIDATE>", "").lower() == "true":
+            validation_func(self, fm_step_json)
+
+    return wrapper
+
+
 class Design2Params(ForwardModelStepPlugin):
     def __init__(self):
         super().__init__(
@@ -55,12 +65,11 @@ def validate_pre_realization_run(
     ) -> ForwardModelStepJSON:
         return fm_step_json
 
+    @validation_enabled
     def validate_pre_experiment(self, fm_step_json: ForwardModelStepJSON) -> None:
-        should_fail_on_validation_error = (
-            fm_step_json.get("argList")[2].lower() == "true"
-        )
-        if should_fail_on_validation_error:
-            DesignKWScript.validate_configuration(fm_step_json.get("argList")[0])
+        template_file_name = self.private_args["<template_file>"]
+        DesignKWScript.validate_configuration(template_file_name=template_file_name)
+        return fm_step_json
 
     @staticmethod
     def documentation() -> Optional[ForwardModelStepDocumentation]: