[BUG] App crashes due to unsafe access on null values from storage #145
Description
Description:
The application crashes at runtime with the following error:
TypeError: Cannot read properties of null (reading 'length')
This occurs when the app attempts to access .length on a value retrieved from localStorage (or similar storage) that is null.
This commonly happens for new users / fresh sessions where expected keys are not yet present in storage.
Steps to Reproduce
Open the app in a fresh browser session (clear localStorage / incognito).
Navigate through the app until storage cleanup or quote-related logic runs.
The app crashes with:
Cannot read properties of null (reading 'length')
Expected Behavior
The app should safely handle missing or unset storage values and not crash.
Actual Behavior
The app crashes because .length is accessed on a null value.
Root Cause (Analysis)
Code assumes values from storage are always non-null, for example:
const value = localStorage.getItem(key);
if (value.length > 0) { ... } // crashes if value === null
However, localStorage.getItem() returns null if the key does not exist.
Suggested Fix
Add defensive checks or defaults before accessing .length, for example:
const value = localStorage.getItem(key);
if (!value) return;
if (value.length > 0) {
...
}
or:
const value = JSON.parse(localStorage.getItem(key) ?? "[]");
Impact
🚨 Causes hard crashes
🚨 Affects new users
🚨 Breaks core functionality
🚨 Generates excessive error reports (Sentry)
Environment
Frontend: React + Vite
Browser: Any
Reproducible: Yes (100% on fresh storage)
Additional Notes
This issue can be resolved by adding simple null guards and/or safe parsing when accessing storage values.