defensive null handling

Always handle nullable values explicitly and defensively to prevent runtime null/undefined errors and to make intent clear. Why: Nulls and undefined values cause intermittent runtime exceptions and unclear state transitions. Being explicit—both when clearing values and when checking inputs—reduces bugs and documents intent.

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Prompt

Reviewer Prompt
Deploy Agent

Always handle nullable values explicitly and defensively to prevent runtime null/undefined errors and to make intent clear.

Why: Nulls and undefined values cause intermittent runtime exceptions and unclear state transitions. Being explicit—both when clearing values and when checking inputs—reduces bugs and documents intent.

Rules to follow:

  • Use optional chaining or explicit null/undefined checks before accessing properties or collection lengths (e.g., workspaceList?.length).
  • Wrap parsing/decoding in try/catch and set values to null when parsing fails or data is absent to represent a cleared value.
  • When multiple related conditions control behavior, combine them so the intended branch is obvious and you don’t accidentally act on a null value.

Examples (based on discussion snippets): 1) Defensive parsing and explicit null to clear state

try { const decodedCmd = atob(cmd.data.cmd64); rtInfo[“shell:lastcmd”] = decodedCmd; } catch (e) { console.error(“Error decoding cmd64:”, e); // null used intentionally to clear the key rtInfo[“shell:lastcmd”] = null; }

2) Combine guards and use optional chaining for nullable collections

if (ww?.workspaceId === workspaceId) { if (workspaceList?.length > 1) { // switch workspace } else { // delete workspace } }

Apply these consistently: prefer explicit null to indicate cleared/absent values, guard all external inputs and collections with optional chaining or null checks, and structure conditionals to make null-handling intent obvious.

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