Don’t reload to a supplemental file.

Fixes #6026

src/project/serve/watch.ts

@@ -177,13 +177,25 @@ export function watchProject(
                   resourceFiles,
                   project!,
                 );
+
+                // Filter out supplmental files (e.g. files that were injected as supplements)
+                // to the render. Instead, we should return the first non-supplemental file.
+                // Example of supplemental file is a user rendering a post that appears in a listing
+                // - the listing will be added as a supplement since changes in the post may change the
+                // listing itself
+                const nonSupplementalFiles = result.files.filter(
+                  (renderResultFile) => {
+                    return !renderResultFile.supplemental;
+                  },
+                );
+
                 return {
                   config: false,
                   output: true,
-                  reloadTarget:
-                    (result.files.length && !isPdfContent(result.files[0].file))
-                      ? join(outputDir, result.files[0].file)
-                      : undefined,
+                  reloadTarget: (nonSupplementalFiles.length &&
+                      !isPdfContent(nonSupplementalFiles[0].file))
+                    ? join(outputDir, nonSupplementalFiles[0].file)
+                    : undefined,
                 };
               }
             } finally {