only add yaml blocks to metadata when they're individually objects. Closes #903

Author: cscheid

src/core/yaml.ts

@@ -100,9 +100,14 @@ export function readYamlFromMarkdown(
         (yamlBlock.trim().length > 0)
       ) {
         // surface errors immediately for invalid yaml
-        parse(yamlBlock, { json: true, schema: QuartoJSONSchema });
-        // add it
-        yaml += yamlBlock;
+        const result = parse(yamlBlock, {
+          json: true,
+          schema: QuartoJSONSchema,
+        });
+        // add it only if it's an actual block
+        if (typeof result !== "string") {
+          yaml += yamlBlock;
+        }
       }
 
       match = kRegExYAML.exec(markdown);

tests/docs/yaml/yaml-parse-dashes.qmd

@@ -0,0 +1,13 @@
+---
+title: "A title"
+---
+
+## Intro
+
+--- 
+
+This will break things.
+
+--- 
+
+#### More

tests/smoke/yaml/core-yaml-dashes.test.ts

@@ -0,0 +1,13 @@
+/*
+* core-yaml-dashes.test.ts
+*
+* Copyright (C) 2022 by RStudio, PBC
+*
+*/
+
+import * as utils from "../../utils.ts";
+import * as render from "../render/render.ts";
+
+const input = utils.docs("yaml/yaml-parse-dashes.qmd");
+
+render.testRender(input, "revealjs", false);