Refuse a carry fence naming a type no info string carries back

corpus/errors/carry-fence-type-unspellable.error

@@ -0,0 +1 @@
+unsupported-node-shape

corpus/errors/carry-fence-type-unspellable.md

@@ -0,0 +1,3 @@
+```adf:\\
+{}
+```

src/markdown/opaque-carry.ts

@@ -33,6 +33,9 @@ export function carriedInline(node: AdfNode, path: ConvertErrorPath): Result<str
 }
 
 export function readCarriedBlock(type: string, body: string, depth: number): Read<AdfNode> {
+  if (type !== '' && !infoStringCarries(type)) {
+    return { fault: unsupportedNodeShape(`the carry fence names a type no info string carries back: spell it ${carryFencePrefix} with the type in the JSON`) }
+  }
   const read = readCarriedJson(body, 'two-space', largestNesting - depth, type)
   if (read.fault !== undefined || type !== '' || !infoStringCarries(read.value.type)) return read
   return { fault: unsupportedNodeShape(`the carry fence names a type its info string carries: spell it ${carryFencePrefix}${read.value.type}`) }

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

@@ -375,6 +375,8 @@ test('reads the carry fence back to the node its info string names and its JSON
   )
   assert.equal(content(markdownToAdf('```adf:\n{\n  "type": "blockCard"\n}\n```\n')), 'unsupported-node-shape: the carry fence names a type its info string carries: spell it adf:blockCard')
   assert.equal(content(markdownToAdf('```adf:\n{}\n```\n')), "unsupported-node-shape: the opaque carry holds one ADF node's JSON: this JSON is no ADF node")
+  const unnamed = 'unsupported-node-shape: the carry fence names a type no info string carries back: spell it adf: with the type in the JSON'
+  assert.equal(content(markdownToAdf('```adf:\\\\\n{}\n```\n')), unnamed)
 })
 
 test('reads the inline carry back to the node its json attribute holds', () => {