erp5_web_renderjs_ui: use 'error' class for validation errors

i need it because use span for displaying icons in json form

bt5/erp5_web_renderjs_ui/PathTemplateItem/web_page_module/rjs_gadget_erp5_label_field_js.js

@@ -141,6 +141,7 @@
         if (this.state.error_text) {
           if (span === null) {
             span = document.createElement('span');
+            span.setAttribute('class', 'error');
             span.textContent = this.state.error_text;
             this.props.container_element.appendChild(span);
           } else {

bt5/erp5_web_renderjs_ui/PathTemplateItem/web_page_module/rjs_gadget_erp5_nojqm_css.css

@@ -1190,11 +1190,11 @@ div[data-gadget-scope='header'] .ui-header ul {
 .gadget-content form .ui-field-contain {
   position: relative;
 }
-.gadget-content form .ui-field-contain > span {
+.gadget-content form .ui-field-contain > span.error {
   animation: fadein 0.2s ease-out;
 }
 @media not screen and (max-width: 85em), only screen and (min-width: 45em) and (max-width: 85em) {
-  .gadget-content form .ui-field-contain > span {
+  .gadget-content form .ui-field-contain > span.error {
     background-color: #FF6600;
     color: #f8fff3;
     left: 25%;
@@ -1206,7 +1206,7 @@ div[data-gadget-scope='header'] .ui-header ul {
     width: auto;
     z-index: 1001;
   }
-  .gadget-content form .ui-field-contain > span:before {
+  .gadget-content form .ui-field-contain > span.error:before {
     position: absolute;
     top: 100%;
     left: 2em;
@@ -1218,7 +1218,7 @@ div[data-gadget-scope='header'] .ui-header ul {
   }
 }
 @media not screen and (min-width: 45em) {
-  .gadget-content form .ui-field-contain > span {
+  .gadget-content form .ui-field-contain > span.error {
     margin-left: 6pt;
     color: #FF6600;
   }

bt5/erp5_web_renderjs_ui/SkinTemplateItem/portal_skins/erp5_web_renderjs_ui/erp5css.less.txt

@@ -1403,7 +1403,7 @@ div[data-gadget-scope='header'] .ui-header {
     // relative for displaying popups with errors
     position: relative;
 
-    & > span {
+    & > span.error {
       animation: fadein @transition-timing;
 
       @media @desktop, @tablet {