Backlink insertion is idempotent

Prior to this, there was no newline between the text prior to the backlinks
which caused it to not properly detect the backlink section.

Author: aaronjensen

lib/updateBacklinks.ts

@@ -82,13 +82,23 @@ export default function updateBacklinks(
             )
             .join("")}`
       )
-      .join("")}\n`;
+      .join("")}`.trim();
   }
 
-  const newNoteContents =
-    noteContents.slice(0, insertionOffset) +
-    backlinksString +
-    noteContents.slice(oldEndOffset);
+  let newNoteContents = noteContents;
+
+  if (backlinksString) {
+    let end = noteContents.slice(oldEndOffset).trim()
+
+    if (end) {
+      end = `\n${end}\n`;
+    }
+
+    newNoteContents =
+      noteContents.slice(0, insertionOffset).trimEnd() + "\n\n" +
+      backlinksString + "\n" +
+      end
+  }
 
   return newNoteContents;
 }