5c: report the depth cause from the guards, and make the publish converge

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

@@ -336,14 +336,15 @@ test('refuses marks and attributes nested deeper than the emitter carries', () =
   assert.equal(code(adfToMarkdown(document(paragraph({ marks, text: 'x', type: 'text' })))), 'unsupported-nesting-depth')
   let attrs: AdfMark['attrs'] = { depth: 'x' }
   for (let depth = 0; depth < 600; depth += 1) attrs = { depth: attrs }
-  const deeper = `unsupported-nesting-depth: an attribute value nests deeper than the ${largestNesting} levels the emitter carries`
-  assert.equal(markdown(adfToMarkdown(document(paragraph({ marks: [{ attrs, type: 'em' }], text: 'x', type: 'text' })))), deeper)
+  const deeper = (key: string, type: string): string =>
+    `unsupported-nesting-depth: the ${key} attribute of ${type} nests deeper than the ${largestNesting} levels an attribute carries`
+  assert.equal(markdown(adfToMarkdown(document(paragraph({ marks: [{ attrs, type: 'em' }], text: 'x', type: 'text' })))), deeper('depth', 'em'))
   const card = (levels: number): AdfNode => {
     let data: JsonValue = 1
     for (let level = 0; level < levels; level += 1) data = [data]
     return { attrs: { data, url: 'https://example.com/a' }, type: 'inlineCard' }
   }
-  assert.equal(markdown(adfToMarkdown(document(paragraph(card(largestNesting + 1))))), deeper)
+  assert.equal(markdown(adfToMarkdown(document(paragraph(card(largestNesting + 1))))), deeper('data', 'inlineCard'))
   assert.deepEqual(path(adfToMarkdown(document(paragraph(card(largestNesting + 1))))), [])
   const spelled = adfToMarkdown(document(paragraph(card(largestNesting))))
   assert.ok(spelled.ok, spelled.ok ? '' : spelled.error.message)

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

@@ -4,7 +4,7 @@ import { adfDocumentFault, carriesOnly } from '../../adf/document.ts'
 import { blockDirective } from '../../adf/block-directives.ts'
 import { carriedBlock } from '../opaque-carry.ts'
 import { emitInlineLine } from './inline-line.ts'
-import { failure, success, type ConvertErrorPath, type Result } from '../../result.ts'
+import { failure, faulted, success, type ConvertErrorPath, type Result } from '../../result.ts'
 import { fencedCodeBlock } from '../backtick-runs.ts'
 import { holdsNullCharacter, isThematicBreak, markerInterruptsParagraph } from '../commonmark-grammar.ts'
 import { languageSlot } from '../code-language.ts'
@@ -24,10 +24,7 @@ const largestListMarker = 999999999
 
 export function adfToMarkdown(document: AdfDocument): Result<string> {
   const fault = adfDocumentFault(document)
-  if (fault !== undefined && adfDocumentFault(document, Number.POSITIVE_INFINITY) === undefined) {
-    return failure('unsupported-nesting-depth', `an attribute value nests deeper than the ${largestNesting} levels the emitter carries`, [])
-  }
-  if (fault !== undefined) return failure('not-an-adf-document', fault, [])
+  if (fault !== undefined) return faulted(fault, [])
   if (document.version !== 1) return failure('unsupported-document-version', `no markdown spelling carries ADF version ${document.version}`, [])
   const blocks = emitBlocks(document.content ?? [], 'document', [], 0)
   if (!blocks.ok) return blocks