fix: don't crash on statically-evaluated expressions that throw (BigInt mixing)

[styfle]

Problem

The static evaluator (src/utils/static-eval.js) applies JS operators directly to known values, but some of those operations can throw at evaluation time:

• BigInt mixing: null + 1n → TypeError: Cannot mix BigInt and other types, use explicit conversions
• Unary + on a BigInt: +1n → TypeError: Cannot convert a BigInt value to a number

The loader statically evaluates the RHS of every top-level-bound assignment (to track known bindings), so real-world code hits this. dd-trace 5's appsec/downstream_requests.js does:

let globalRequestCounter

function enable (_config) {
  globalRequestCounter = 0n
}

function disable () {
  globalRequestCounter = null   // <- registers null as the known binding value
}

function shouldSampleBody (req, outgoingUrl) {
  // evaluator computes `null + 1n` here and throws, crashing the build
  globalRequestCounter = (globalRequestCounter + 1n) & UINT64_MAX
  ...
}

The uncaught TypeError kills the whole compilation — e.g. ncc build of anything depending on dd-trace@5 dies with:

TypeError: Cannot mix BigInt and other types, use explicit conversions
    at Object.BinaryExpression (.../relocate-loader.js.cache.js:...)
    at walk (...)
    at computePureStaticValue (...)

This blocks bumping dd-trace 4 → 5 in any ncc-bundled project (every ncc version is affected since they all bundle this loader).

Fix

Wrap the operator application in BinaryExpression and UnaryExpression in try/catch, so a throwing expression is treated as not statically computable (the evaluator's existing "unknown value" semantics). CallExpression and NewExpression already handle evaluation errors exactly this way, so this follows established convention in the file. The diff is best viewed with whitespace ignored.

Test

Added test/unit/static-eval-bigint reproducing the dd-trace pattern (known-null binding + 1n, BigInt consts, and unary + on a known BigInt). Without the fix it crashes the build with the errors above; with the fix the module passes through untouched.

npx jest test/index.test.js: 85/85 pass. (test/project.test.js fails identically on unmodified main in my environment — pre-existing, unrelated.)

🤖 Generated with Claude Code

Related

• Related to TypeError with BigInt data types ncc#1307
• Related to fix(static-eval): skip evaluation when BigInt values are involved #208