fix: ensure validation takes place

Part of coop-cloud/organising#243 (comment).

pkg/upstream/stack/loader.go

@@ -13,6 +13,11 @@ import (
 	"github.com/sirupsen/logrus"
 )
 
+// DontSkipValidation ensures validation is done for compose file loading
+func DontSkipValidation(opts *loader.Options) {
+	opts.SkipValidation = false
+}
+
 // LoadComposefile parse the composefile specified in the cli and returns its Config and version.
 func LoadComposefile(opts Deploy, appEnv map[string]string) (*composetypes.Config, error) {
 	configDetails, err := getConfigDetails(opts.Composefiles, appEnv)
@@ -21,13 +26,12 @@ func LoadComposefile(opts Deploy, appEnv map[string]string) (*composetypes.Confi
 	}
 
 	dicts := getDictsFrom(configDetails.ConfigFiles)
-	config, err := loader.Load(configDetails)
+	config, err := loader.Load(configDetails, DontSkipValidation)
 	if err != nil {
 		if fpe, ok := err.(*loader.ForbiddenPropertiesError); ok {
 			return nil, fmt.Errorf("compose file contains unsupported options:\n\n%s",
 				propertyWarnings(fpe.Properties))
 		}
-
 		return nil, err
 	}