fix(variables): Improve `getNodeUsedVars` implementation details

* Validate the `conditions` within each case of `If-Else` nodes
* Validate content in `classes`  of `QuestionClassifier` nodes

web/app/components/workflow/nodes/_base/components/variable/utils.ts

@@ -975,6 +975,7 @@ export const getNodeUsedVars = (node: Node): ValueSelector[] => {
       res = (data as IfElseNodeType).conditions?.map((c) => {
         return c.variable_selector || []
       }) || []
+      res.push(...((data as IfElseNodeType).cases || []).flatMap(c => (c.conditions || [])).map(c => c.variable_selector || []))
       break
     }
     case BlockEnum.Code: {
@@ -994,6 +995,9 @@ export const getNodeUsedVars = (node: Node): ValueSelector[] => {
       res = [payload.query_variable_selector]
       const varInInstructions = matchNotSystemVars([payload.instruction || ''])
       res.push(...varInInstructions)
+
+      const classes = payload.classes.map(c => c.name)
+      res.push(...matchNotSystemVars(classes))
       break
     }
     case BlockEnum.HttpRequest: {