improve error propagation by removing extra, not translatable eiffel error

src/app/eiffel/parser.go

@@ -286,6 +286,10 @@ func (bt *BasicTemplate) Parse(ctx context.Context, ruleParsers *RuleParserProvi
 	return result, nil
 }
 
+// Validate makes sure that the template is valid. It checks the structure of and semantic of the values inside.
+// Each rule configuration is validated by the corresponding rule parser.
+// It returns a slice of validation errors that are safe to show to the user (translatable).
+// In almost any case, the returned slice will contain the template.ErrInvalidTemplate error.
 func (bt *BasicTemplate) Validate(v validation.V, ruleParsers *RuleParserProvider) []error {
 	errs := validation.Validate("", "", bt, RuleReferencesValidator)
 	if len(errs) > 0 {
@@ -294,7 +298,7 @@ func (bt *BasicTemplate) Validate(v validation.V, ruleParsers *RuleParserProvide
 
 	err, validationErrs := v.ValidateStruct(bt)
 	if err != nil {
-		return []error{err}
+		return []error{t.ErrInvalidTemplate, err}
 	}
 
 	// Unfortunately, validation is currently not capable of validating slices/maps of structs.
@@ -302,14 +306,14 @@ func (bt *BasicTemplate) Validate(v validation.V, ruleParsers *RuleParserProvide
 	for _, rule := range bt.Rules {
 		err, ruleValidationErrs := v.ValidateStruct(rule) // this is validating the generic rule struct
 		if err != nil {
-			return []error{err}
+			return []error{t.ErrInvalidTemplate, err}
 		}
 
 		validationErrs = append(validationErrs, ruleValidationErrs...)
 
 		ruleParser, err := ruleParsers.Parser(rule.Type)
 		if err != nil {
-			return []error{err}
+			return []error{t.ErrInvalidTemplate, err}
 		}
 
 		// This is requesting the rule parser to validate the rule value.
@@ -321,7 +325,7 @@ func (bt *BasicTemplate) Validate(v validation.V, ruleParsers *RuleParserProvide
 	for _, variant := range bt.Variants {
 		err, variantValidationErrs := v.ValidateStruct(variant)
 		if err != nil {
-			return []error{err}
+			return []error{t.ErrInvalidTemplate, err}
 		}
 
 		validationErrs = append(validationErrs, variantValidationErrs...)

src/app/eiffel/web.go

@@ -13,7 +13,6 @@ import (
 	"github.com/org-harmony/harmony/src/core/hctx"
 	"github.com/org-harmony/harmony/src/core/persistence"
 	"github.com/org-harmony/harmony/src/core/util"
-	"github.com/org-harmony/harmony/src/core/validation"
 	"github.com/org-harmony/harmony/src/core/web"
 	"net/http"
 	"path/filepath"
@@ -134,7 +133,6 @@ func subscribeEvents(appCtx *hctx.AppCtx) {
 		validationErrs := ebt.Validate(appCtx.Validator, RuleParsers())
 		if len(validationErrs) > 0 {
 			validateEvent.AddErrors(validationErrs...)
-			validateEvent.AddErrors(validation.Error{Msg: "eiffel.parser.error.invalid-template"})
 			return nil
 		}