fix(jupyter): error message when install fails due to jupyter command not being on PATH (#21767)

We were failing silently in this scenario.

cli/tests/integration/jupyter_tests.rs

@@ -0,0 +1,8 @@
+// Copyright 2018-2024 the Deno authors. All rights reserved. MIT license.
+
+itest!(jupyter_install_command_not_exists {
+  args: "jupyter --unstable --install",
+  output: "jupyter/install_command_not_exists.out",
+  envs: vec![("PATH".to_string(), "".to_string())],
+  exit_code: 1,
+});

cli/tests/integration/mod.rs

@@ -121,7 +121,10 @@ mod inspector;
 mod install;
 #[path = "js_unit_tests.rs"]
 mod js_unit_tests;
-mod jsr_tests;
+#[path = "jsr_tests.rs"]
+mod jsr;
+#[path = "jupyter_tests.rs"]
+mod jupyter;
 #[path = "lint_tests.rs"]
 mod lint;
 #[path = "lsp_tests.rs"]

cli/tests/testdata/jupyter/install_command_not_exists.out

@@ -0,0 +1,4 @@
+error: Failed to spawn 'jupyter' command. Is JupyterLab installed (https://jupyter.org/install) and available on the PATH?
+
+Caused by:
+[WILDCARD]

cli/tools/jupyter/install.rs

@@ -6,6 +6,7 @@ use deno_core::error::AnyError;
 use deno_core::serde_json;
 use deno_core::serde_json::json;
 use std::env::current_exe;
+use std::io::ErrorKind;
 use std::io::Write;
 use std::path::Path;
 use tempfile::TempDir;
@@ -76,19 +77,34 @@ pub fn install() -> Result<(), AnyError> {
       &temp_dir.path().to_string_lossy(),
     ])
     .spawn();
+  let mut child = match child_result {
+    Ok(child) => child,
+    Err(err)
+      if matches!(
+        err.kind(),
+        ErrorKind::NotFound | ErrorKind::PermissionDenied
+      ) =>
+    {
+      return Err(err).context(concat!(
+        "Failed to spawn 'jupyter' command. Is JupyterLab installed ",
+        "(https://jupyter.org/install) and available on the PATH?"
+      ));
+    }
+    Err(err) => {
+      return Err(err).context("Failed to spawn 'jupyter' command.");
+    }
+  };
 
-  if let Ok(mut child) = child_result {
-    let wait_result = child.wait();
-    match wait_result {
-      Ok(status) => {
-        if !status.success() {
-          bail!("Failed to install kernelspec, try again.");
-        }
-      }
-      Err(err) => {
-        bail!("Failed to install kernelspec: {}", err);
+  let wait_result = child.wait();
+  match wait_result {
+    Ok(status) => {
+      if !status.success() {
+        bail!("Failed to install kernelspec, try again.");
       }
     }
+    Err(err) => {
+      bail!("Failed to install kernelspec: {}", err);
+    }
   }
 
   let _ = std::fs::remove_dir(temp_dir);