Guard nullable values

Always check for null/undefined before accessing values or rendering UI instead of relying on non‑null assertions or unconditional usage. Prefer optional chaining and explicit guards in logic and conditional rendering in JSX.

Why: Non-null assertions (!) and unconditional rendering can cause runtime exceptions when data is absent. Explicit checks make intent clear and avoid crashes.

How to apply:

• Replace ! assertions with optional chaining and guards:
  • Bad: let relationId = only(edge.data.relations)!.id;
  • Good: let relationId = only(edge.data.relations)?.id; if (relationId) { /* use relationId */ }
• Conditionally render components only when required data exists:
  • Bad: <LikeC4CustomColors customColors={view.customColorDefinitions} />
  • Good: {view.customColorDefinitions && ( <LikeC4CustomColors customColors={view.customColorDefinitions} /> )}

Notes:

• Use optional chaining (?.) when a property may be undefined; follow with an if-check if you need to act on the value.
• For JSX, prefer conditional rendering or early returns to avoid passing undefined props or rendering components that expect data.
• Reserve ! only when you can guarantee the value (and document why). When in doubt, guard.