fixup rmd 'always_allow_html' error message (#1729)

fixup rmd 'always_allow_html' error message (#1729)

Author: cscheid

news/changelog-1.1.md

@@ -8,6 +8,10 @@
 
 - Correct handling of `knitr::include_graphics()` within inline expressions.
 
+# RMarkdown
+
+- improve error message for HTML being emitted in non-HTMl formats (#1745)
+
 ## Pandoc
 
 - Update to Pandoc 2.19

src/execute/rmd.ts

@@ -116,6 +116,8 @@ export const knitrEngine: ExecutionEngine = {
           );
         }
 
+        output = filterAlwaysAllowHtml(output);
+
         return output;
       },
     );
@@ -283,3 +285,16 @@ async function printCallRDiagnostics() {
     info("");
   }
 }
+
+function filterAlwaysAllowHtml(s: string): string {
+  if (
+    s.indexOf(
+      "Functions that produce HTML output found in document targeting",
+    ) !== -1
+  ) {
+    s = s
+      .replace("your rmarkdown file", "your quarto file")
+      .replace("always_allow_html: true", "prefer-html: true");
+  }
+  return s;
+}