fix(jupyter): keep `this` around (#20789)

This fixes #20767.

We were losing `this` and then when an exception was happening, it
didn't show up in the output because we weren't bubbling up exceptions
from within a user defined function for displaying. I thought about
doing a `.call(object)` but didn't want to get in the way of a bound
`this` that a user or library was already putting on the function.

1 files changed, 3 insertions, 4 deletions

diff --git a/cli/tools/jupyter/server.rs b/cli/tools/jupyter/server.rs
index 2489fcd04..0b8d25c3e 100644
--- a/cli/tools/jupyter/server.rs
+++ b/cli/tools/jupyter/server.rs
@@ -554,14 +554,13 @@ async fn get_jupyter_display(
       "Runtime.callFunctionOn",
       Some(json!({
         "functionDeclaration": r#"function (object) {
-      const display = object[Symbol.for("Jupyter.display")];
-
-      if (typeof display !== "function") {
+      if (typeof object[Symbol.for("Jupyter.display")] !== "function") {
         return null;
       }
       
       try {
-        return JSON.stringify(display());
+        const representation = object[Symbol.for("Jupyter.display")]();
+        return JSON.stringify(representation);
       } catch {
         return null;
       }