Use 1 based index to index cells

Author: dragonstyle

src/core/jupyter/jupyter-embed.ts

@@ -256,12 +256,12 @@ async function notebookMarkdown(
   } else if (nbAddress.indexes) {
     // Filter and sort based upon cell indexes
     const theCells = nbAddress.indexes.map((idx) => {
-      if (idx < 0 || idx >= notebookInfo.outputs.length) {
+      if (idx < 1 || idx >= notebookInfo.outputs.length) {
         throw new Error(
           `The cell index ${idx} isn't within the range of cells`,
         );
       }
-      return notebookInfo.outputs[idx];
+      return notebookInfo.outputs[idx - 1];
     });
     return notebookMarkdown(theCells, notebookInfo.title);
   } else {