feat: display allowed values when vars are not provided (#2052)

requires.go

@@ -12,16 +12,19 @@ func (e *Executor) areTaskRequiredVarsSet(t *ast.Task) error {
 		return nil
 	}
 
-	var missingVars []string
+	var missingVars []errors.MissingVar
 	for _, requiredVar := range t.Requires.Vars {
 		_, ok := t.Vars.Get(requiredVar.Name)
 		if !ok {
-			missingVars = append(missingVars, requiredVar.Name)
+			missingVars = append(missingVars, errors.MissingVar{
+				Name:          requiredVar.Name,
+				AllowedValues: requiredVar.Enum,
+			})
 		}
 	}
 
 	if len(missingVars) > 0 {
-		return &errors.TaskMissingRequiredVars{
+		return &errors.TaskMissingRequiredVarsError{
 			TaskName:    t.Name(),
 			MissingVars: missingVars,
 		}
@@ -51,7 +54,7 @@ func (e *Executor) areTaskRequiredVarsAllowedValuesSet(t *ast.Task) error {
 	}
 
 	if len(notAllowedValuesVars) > 0 {
-		return &errors.TaskNotAllowedVars{
+		return &errors.TaskNotAllowedVarsError{
 			TaskName:       t.Name(),
 			NotAllowedVars: notAllowedValuesVars,
 		}