`react-doctor/no-non-null-assertion-on-maybe-undefined-result`

Non-null assertion on a maybe-undefined result

Category: Bugs
Severity: warn
Source: oxlint-plugin-react-doctor
Framework: global
Enabled when: always
Default: Enabled

Validate the diagnostic

Confirm the reported code matches this rule before you edit it.

Confirm the reported code matches react-doctor/no-non-null-assertion-on-maybe-undefined-result. Compare it with the Before example and verify the same API, framework, and execution context. Treat it as a false positive only when one of those conditions differs.

Compare the code

The corrected pattern shows a focused way to address the diagnostic.

Reported pattern

function selectUser(users: User[], id: string) {
  if (!users.some((user) => user.isActive)) return null;
  return users.find((user) => user.id === id)!.name;
}

Corrected pattern

function selectUser(users: User[], id: string) {
  if (!users.some((user) => user.isActive)) return null;
  const selectedUser = users.find((user) => user.id === id);
  return selectedUser?.name ?? null;
}

How to fix

Use the corrected pattern as a reference. Preserve behavior that the rule does not require you to change.

Copyable fix prompt

Copy this self-contained prompt into your coding agent after you confirm the diagnostic.

Fix every confirmed react-doctor/no-non-null-assertion-on-maybe-undefined-result diagnostic in the current repository. Required change: - Remove the non-null assertion from .find(), .match(), and .get() results. Handle the missing result with optional chaining, a guard, or a fallback.

Reference transformation:Before:

function selectUser(users: User[], id: string) {
  if (!users.some((user) => user.isActive)) return null;
  return users.find((user) => user.id === id)!.name;
}

After:

function selectUser(users: User[], id: string) {
  if (!users.some((user) => user.isActive)) return null;
  const selectedUser = users.find((user) => user.id === id);
  return selectedUser?.name ?? null;
}

Constraints: - Confirm the reported code matches the Before pattern. - Make the smallest change that fixes the root cause. - Preserve behavior and interfaces unrelated to this diagnostic. - Reuse existing project components, utilities, and conventions. - Do not introduce render-phase side effects, render-phase state updates, or Hooks rule violations. - Adapt identifiers and framework details instead of copying blindly. - Do not disable the rule or suppress matching code. Verification: - Run focused tests for the changed behavior. - Run React Doctor and confirm this diagnostic no longer appears. - Report the files changed and any checks you could not run.

More Bugs rules from the rules reference:

react-doctor/no-nondeterministic-id-value-in-render-body: Nondeterministic id generated in render body
react-doctor/no-nullish-coalescing-arithmetic-precedence: Nullish coalescing swallowed by adjacent arithmetic
react-doctor/no-object-keys-values-entries-on-maybe-undefined: Object.keys/values/entries on maybe-undefined value
react-doctor/no-object-or-array-coerced-to-string-in-template-literal: Object or lossy array coerced in a template literal
react-doctor/no-pass-data-to-parent: Disallow passing data to parents in an effect.

react-doctor/no-non-null-assertion-on-maybe-undefined-result