fix: correctly check for length of array

Author: kandolfp

src/core/jupyter/jupyter.ts

@@ -1555,11 +1555,18 @@ async function mdFromCodeCell(
 
     for (const { index, output } of sortedOutputs) {
       // compute output label
-      const outputLabel = label && (labelCellContainer || Array.isArray(sortedOutputs)) && isDisplayData(output)
+      const outputLabel = label &&
+        (
+          labelCellContainer ||
+          (Array.isArray(sortedOutputs) && (sortedOutputs.length > 1))
+        ) &&
+        isDisplayData(output)
         ? (label + "-" + nextOutputSuffix++)
         : label;
       // If the user specifies a top-level array for images but also labels give a warning.
-      if (labelCellContainer === false && Array.isArray(sortedOutputs) == true) {
+      if (labelCellContainer === false &&
+        (Array.isArray(sortedOutputs) == true && (sortedOutputs.length > 1))
+      ) {
         warning("Warning: using multiple top-level figures with labels might result in unwanted behaviour.")
       }
       // If this output has been marked to not be displayed