Answer stability round 1: the docs name V8's array limit in one text node, a test pins Invalid array length, and item 106 takes the readers' RangeError and JavaScriptCore's Out of memory

src/markdown/emit/adf-to-markdown.test.ts

@@ -49,7 +49,7 @@ test('refuses a document whose markdown runs past the engine\'s longest string',
   let value: JsonValue = new Array<JsonValue>(2_200_000).fill(0)
   for (let level = 0; level < 495; level += 1) value = [value]
   const result = adfToLosslessMarkdown(document({ attrs: { value }, type: 'unknownBlock' }))
-  assert.match(markdown(result), /^unsupported-node-shape: the output runs past what this JavaScript engine holds: /)
+  assert.match(markdown(result), /^unsupported-node-shape: the output would be longer than the longest string or array this JavaScript engine builds \(/)
   assert.deepEqual(path(result), [])
 })
 

src/result.test.ts

@@ -4,7 +4,11 @@ import { fileURLToPath } from 'node:url'
 import { readFileSync, readdirSync } from 'node:fs'
 import test from 'node:test'
 
-import { success, withinEngineLimits } from './result.ts'
+import { success, withinEngineLimits, type Result } from './result.ts'
+
+function code(result: Result<string>): string {
+  return result.ok ? `converted ${result.value}` : result.error.code
+}
 
 const sourceRoot = dirname(fileURLToPath(import.meta.url))
 const union = /export type ConvertErrorCode =\n((?:\s+\| '[a-z-]+'\n)+)/
@@ -39,7 +43,15 @@ test('refuses where SpiderMonkey runs out of string, and lets a stack overflow o
     withinEngineLimits(() => {
       throw overflow
     }),
-    { error: { code: 'unsupported-node-shape', message: 'the output runs past what this JavaScript engine holds: allocation size overflow', path: [] }, ok: false },
+    { error: { code: 'unsupported-node-shape', message: 'the output would be longer than the longest string or array this JavaScript engine builds (allocation size overflow)', path: [] }, ok: false },
+  )
+  assert.equal(
+    code(
+      withinEngineLimits(() => {
+        throw new RangeError('Invalid array length')
+      }),
+    ),
+    'unsupported-node-shape',
   )
   assert.throws(() =>
     withinEngineLimits(() => {

src/result.ts

@@ -52,6 +52,6 @@ export function withinEngineLimits<T>(convert: () => Result<T>): Result<T> {
   } catch (error) {
     // A stack overflow is a bug (docs/decisions.md §Nothing recurses unbounded), so it stays a throw.
     if (!(error instanceof Error) || !engineLimitThrows.includes(`${error.name}: ${error.message}`)) throw error
-    return failure('unsupported-node-shape', `the output runs past what this JavaScript engine holds: ${error.message}`, [])
+    return failure('unsupported-node-shape', `the output would be longer than the longest string or array this JavaScript engine builds (${error.message})`, [])
   }
 }