[BUG] Charts Crash When yearlyResults Is Empty or Undefined

[TopBeijing]

Both NetWorthChart and CashOutflowChart components assume that results.yearlyResults is always a non-empty array. If projectionYears is set to 0 or a negative value (e.g., via URL or direct state manipulation), or if calculation logic fails, yearlyResults can be empty. This causes runtime errors (e.g., .map on undefined or empty arrays) and chart rendering failures.

Steps to Reproduce

1. Set projectionYears to 0 or a negative value (e.g., via URL or programmatically).
2. Observe that the charts fail to render and may throw runtime errors.

Expected Behavior

Charts should gracefully handle empty or undefined data, displaying a user-friendly message instead of crashing.

Suggested Fix

Add runtime guards in both chart components to check for empty or undefined yearlyResults and render a fallback UI when no data is available.