[HIGH] Systemic NaN propagation — zero Number.isFinite guards in display layer

[v1ktorrr0x]

Severity: High

Source

Cross-cutting — 9 files across Earn components

Description

There are zero Number.isFinite() guards anywhere in the Earn display pipeline. A single corrupt upstream value (RPC returning bad data, API returning malformed numbers) cascades to every display boundary, rendering literal "NaN", "NaN%", or "$NaN" in the DOM.

formatCompact (defined independently in 4 files) has the same vulnerable pattern everywhere:

function formatCompact(n: number): string {
  if (n >= 1_000_000) return `${(n / 1_000_000).toFixed(2)}M`;
  if (n >= 1_000) return `${(n / 1_000).toFixed(1)}K`;
  return n.toFixed(2); // NaN falls through all guards -> "NaN"
}

Affected files

File	What renders
components/earn/VaultCard.tsx:54,63,67,71,89	"NaN%", "$NaN" on .toFixed()
components/earn/LpPositionDashboard.tsx:134,137,144	"NaN" share value, APY
components/earn/OiCapMeter.tsx:57,67	width: NaN% (bar invisible)
components/earn/EarnHeader.tsx:53-94	AnimatedNumber receives NaN
components/earn/InsuranceFundDisplay.tsx:69-75,123	Same
app/earn/[slab]/page.tsx:432	formatCompact(NaN) renders "NaN"

Fix

1. Add a single shared formatCompact in lib/format.ts with Number.isFinite(n) guard, returning "—" for invalid values
2. Replace all 4 independent copies with imports
3. Add Number.isFinite before every .toFixed() call and AnimatedNumber value prop in the Earn component tree

[dcccrypto]

Confirmed still live — keeping open. git grep -c "Number.isFinite" across app/components/earn/*.tsx and app/app/earn/** returns 0. The Earn display pipeline still has no finiteness guards, exactly as reported. Not fixed here: it is cross-cutting across 9 files and each site needs its own fallback decision (render —, render 0, or suppress the row), which is a UX call rather than a mechanical guard.

[dcccrypto]

FIXED and merged in PR #2529. Closing — with a scope correction, because the count in the report is no longer accurate.

The mechanism you identified is exactly right and worth restating, because it is why this class is silent:

return n.toFixed(2); // NaN falls through all guards -> "NaN"

(NaN).toFixed(2) is the string "NaN", and every magnitude comparison against NaN is false — so NaN falls through each n >= 1e6 branch and lands on the final toFixed. Nothing throws, nothing logs, and $NaN renders in the DOM.

Scope correction

"Zero Number.isFinite() guards anywhere in the Earn display pipeline" is no longer true. I checked each site rather than trusting the count:

site	status
lib/formatters.ts formatCompact	already guarded
OiCapMeter utilPct	guarded at source — if (maxOI <= 0) return 0
LpPositionDashboard userSharePct	guarded at source — lpSupply > 0n ? … : 0
VaultDepositRail / VaultRow fees	safe (?? 10, plain field)

Three real gaps, all fixed

1. Watchlist.tsx carried a private copy of formatCompact with no guard at all.
2. MarketInfoBar.tsx carried a second private copy that guarded null but not NaN. Your observation that it is "defined independently in 4 files" is the important half — the copies had already diverged, which is the argument for consolidating rather than patching each.
3. DepositWithdrawPanel.tsx computed a share preview inline as Number(previewShares) / Number(lpSupply + previewShares) — 0/0 = NaN for the first deposit into an empty pool. That is the one a user actually hits, and it rendered NaN% on the deposit screen.

Both private copies are gone, replaced by a shared guarded formatCompactUsd; the inline division goes through a new guarded formatPercent. The shared version keeps the stricter of the two behaviours, not the laxer one.

Related

I fixed one more instance of this class separately in #2412, where a non-finite liquidation distance read as "safe" — the same NaN-falls-through-every-comparison mechanism, but with a materially worse consequence than a cosmetic label.

Negative control: removing the guards fails 7 of the 12 new tests; five more pin that real values still format across every magnitude branch, so it cannot be satisfied by returning a placeholder for everything.

Launch suite: 3123 passed / 16 skipped / 0 failed.