userhimanshuverma opened a new pull request, #16440:
URL: https://github.com/apache/pinot/pull/16440
#### **Issue**
When browsing ZooKeeper nodes via the Pinot Controller UI (`Zookeeper
Browser` tab), the UI crashes with the following error in the console:
Related to #14216
```
Uncaught (in promise) TypeError: Cannot read properties of null (reading
'numChildren')
```
This issue occurs when `currentNodeListStat[pathName]` is `null` or
`undefined`, which can happen for certain ZNodes that exist but don’t have
associated stat metadata (e.g., if there was a permission issue or deletion in
progress).
This results in a **blank screen** and an unusable UI in certain scenarios.
Screenshots showing the behavior:
* Working cluster shows a warning for `null` nodes:
* Failing cluster crashes on the same condition:
---
#### **Root Cause**
The existing logic assumes all `currentNodeListStat[pathName]` values are
valid objects, and directly accesses `numChildren`. However, in real-world
deployments, `null` values can be returned by ZooKeeper API due to inconsistent
state or authorization limitations.
---
#### **Fix**
Updated the `getZookeeperData` function in `PinotMethodUtils.ts` to:
* Check if `currentNodeListStat[pathName]` is `null` or `undefined`
* Gracefully skip such nodes while logging a warning for visibility
* Avoids UI crashes and ensures the rest of the node tree loads properly
**Updated code snippet:**
```js
pathNames.forEach((pathName) => {
const nodeStat = currentNodeListStat[pathName];
// Skip if nodeStat is null or undefined
if (!nodeStat) {
console.warn(`Skipping null node for path: ${pathName}`);
return;
}
newTreeData[0].child.push({
nodeId: `${counter++}`,
label: pathName,
fullPath: path === '/' ? path + pathName : `${path}/${pathName}`,
child: [],
isLeafNode: nodeStat.numChildren === 0,
hasChildRendered: false
});
});
```
---
#### **Impact**
* Prevents UI from crashing on malformed or permission-limited ZooKeeper
nodes
* Allows continued navigation of valid nodes
* Adds debug logging for `null` node cases to aid further troubleshooting
#### **Issue Screenshot**
<img width="1512" height="903" alt="image"
src="https://github.com/user-attachments/assets/40e505ba-78fb-4674-ab56-a9583939745f";
/>
#### **After Fix Screenshot**
<img width="1512" height="904" alt="image"
src="https://github.com/user-attachments/assets/15394423-d61e-41d6-b3a4-f8a9a505fa6a";
/>
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