fix(validate-semantic): suppress TypeError when reading operationId (#3769)

Definition author can define Operation Object as null. This commit
fixes this edge-case.

Co-authored-by: Paulina Lukasik <[email protected]>

Author: lukasikp

src/plugins/validate-semantic/validators/2and3/operations.js

@@ -6,7 +6,7 @@ export const validate2And3OperationHasUniqueId = () => sys => {
       return nodes.reduce((acc, node) => {
         const value = node.node
 
-        const id = value.operationId
+        const id = value?.operationId
 
         if (id) {
           if (seen.indexOf(id) > -1) {