finallyStatementSafety

Reports control flow statements in finally blocks that can override control flow in try/catch blocks.

✅ This rule is included in the ts logical preset.

Control flow statements such as return, throw, break, and continue in finally blocks can cause unexpected behavior. When these statements appear in a finally block, they override any control flow statements in the corresponding try or catch blocks. The finally block always executes, and its control flow statements take precedence, which can lead to bugs that are difficult to diagnose.

Examples

❌ Incorrect

function processData() {
  try {
    return fetchData();
  } finally {
    return null;
  }
}

function handleError() {
  try {
    throw new Error("Original error");
  } catch (error) {
    throw error;
  } finally {
    throw new Error("Override error");
  }
}

for (let i = 0; i < items.length; i++) {
  try {
    processItem(items[i]);
  } finally {
    break;
  }
}

✅ Correct

function processData() {
  try {
    return fetchData();
  } finally {
    cleanup();
  }
}

function handleError() {
  try {
    throw new Error("Original error");
  } catch (error) {
    console.error(error);
    throw error;
  } finally {
    cleanup();
  }
}

for (let i = 0; i < items.length; i++) {
  try {
    processItem(items[i]);
    break;
  } finally {
    cleanup();
  }
}

Options

This rule is not configurable.

When Not To Use It

If you are very confident in your handling of exception handling in your code and specifically want to use the confusing quirks of finally control flow statements, this rule might not be for you.

Further Reading

• MDN: try…catch
• MDN: Control flow and error handling

Equivalents in Other Linters

• Biome: noUnsafeFinally
• Deno: no-unsafe-finally
• ESLint: no-unsafe-finally
• Oxlint: eslint/no-unsafe-finally