keep evaluateDocument's error boundary around tokenize/parse, not just evaluate

tokenize() and parseLine() ran outside the try/catch, and the parser
has no recursion-depth guard for nested parens. A pathologically
nested line overflowed the stack with an uncaught RangeError, killing
the whole document instead of nulling just that line — the exact
thing evaluateDocument is supposed to prevent.

src/engine/edge.test.ts

@@ -282,3 +282,13 @@ describe("review fixes", () => {
     });
   });
 });
+
+describe("regression 2026-08-12", () => {
+  it("a deeply nested-parens line nulls out just that line, not the whole document", () => {
+    const deep = "(".repeat(50000) + "1" + ")".repeat(50000);
+    const r = eng.evaluateDocument(`1+1\n${deep}\n2+2`).map((x) => x.text);
+    expect(r[0]).toBe("2");
+    expect(r[1]).toBeNull();
+    expect(r[2]).toBe("4");
+  });
+});

src/engine/index.ts

@@ -3,7 +3,7 @@
 import { DateOrder, Decimal, EngineSettings, EvalError, Quantity, Unit, Value, XRefError, defaultSettings, qty } from "./types";
 import { Registry, buildRegistry, Completion } from "./registry";
 import { tokenize, Token } from "./tokenizer";
-import { parseLine } from "./parser";
+import { parseLine, ParsedLine } from "./parser";
 import { evaluate, EvalCtx, XRefResolver, toBase, fromBase } from "./evaluator";
 import { formatValue } from "./formatter";
 import { detectDateOrder } from "./datetime";
@@ -118,12 +118,17 @@ export class SumEngine {
         continue;
       }
 
-      const tokens = tokenize(line, this.reg, this.dateOrder);
+      // tokenize/parseLine/evaluate all run under one try/catch: pathological
-      const knownVars = new Set(vars.keys());
+      // input (e.g. stack-overflowing nested parens in the parser) must null
-      const parsed = parseLine(tokens, knownVars, line);
+      // out this one line, not throw past evaluateDocument and kill the rest.
-
+      let tokens: Token[] = [];
+      let parsed: ParsedLine = { expr: null };
       let value: Value | null = null;
       let lineError: string | undefined;
+      try {
+        tokens = tokenize(line, this.reg, this.dateOrder);
+        const knownVars = new Set(vars.keys());
+        parsed = parseLine(tokens, knownVars, line);
         if (parsed.expr) {
           const ctx: EvalCtx = {
             reg: this.reg,
@@ -132,17 +137,16 @@ export class SumEngine {
             historicalRates: this.historicalRates,
             resolveXRef,
           };
-        try {
-          value = evaluate(parsed.expr, ctx);
           // a line without a result beats a dead sheet.
-          // surface unexpected bugs so the user knows why it failed
+          value = evaluate(parsed.expr, ctx);
+        }
       } catch (e) {
         if (e instanceof XRefError) {
           lineError = e.message;
         } else if (e instanceof EvalError) {
           // Expected evaluation failure; remain silent
         } else {
-            // Surface unexpected bugs/BigInt errors and log them
+          // Surface unexpected bugs/BigInt errors/RangeErrors and log them
           lineError = e instanceof Error ? e.message : String(e);
           console.warn("evaluate failed:", e);
         }
@@ -150,7 +154,6 @@ export class SumEngine {
       }
       if (value?.kind === "quantity" && !value.value.isFinite()) value = null;
       if (value && parsed.assign) vars.set(parsed.assign, value);
-      }
 
       lineValues.push(value);
       lineKinds.push("normal");