Azure Node App (on Windows app service) Failing to Run - node.js

Question

As a starting point for an application, I'm trying to get a simple Hello World running on Node in Azure (on a Windows app service). While the goal will be to push from an Azure DevOps pipeline, for now I'm just deploying from VS Code following this guide.
The application runs locally as expected, and the deploy to Azure is successfully moving the expected files (to include node_modules, package.json, app.js, and the various other code files). But the application is somehow failing to run correctly on Azure.
Any request results in a 500 error, whether for the root URL or explicitly for /app.js. (I was testing the latter to see if it just returned the file, but it's a 500 error.) I've enabled as much logging as I can find in Azure, but no more helpful information has surfaced. Just records of HTTP requests with generic 500 responses.
Some research led me to suspect that I need a web.config to tell IIS to use the node application. Following some samples found online, I've ended up with this:
<?xml version="1.0" encoding="utf-8"?>
<!--
This configuration file is required if iisnode is used to run node processes behind
IIS or IIS Express. For more information, visit:
https://github.com/tjanczuk/iisnode/blob/master/src/samples/configuration/web.config
-->
<configuration>
<system.webServer>
<!-- Visit http://blogs.msdn.com/b/windowsazure/archive/2013/11/14/introduction-to-websockets-on-windows-azure-web-sites.aspx for more information on WebSocket support -->
<webSocket enabled="false" />
<handlers>
<!-- Indicates that the server.js file is a node.js site to be handled by the iisnode module -->
<add name="iisnode" path="app.js" verb="*" modules="iisnode"/>
</handlers>
<rewrite>
<rules>
<!-- Do not interfere with requests for node-inspector debugging -->
<rule name="NodeInspector" patternSyntax="ECMAScript" stopProcessing="true">
<match url="^app.js\/debug[\/]?" />
</rule>
<!-- First we consider whether the incoming URL matches a physical file in the /public folder -->
<rule name="StaticContent">
<action type="Rewrite" url="public{REQUEST_URI}"/>
</rule>
<!-- All other URLs are mapped to the node.js site entry point -->
<rule name="DynamicContent">
<conditions>
<add input="{REQUEST_FILENAME}" matchType="IsFile" negate="True"/>
</conditions>
<action type="Rewrite" url="app.js"/>
</rule>
</rules>
</rewrite>
<!-- 'bin' directory has no special meaning in node.js and apps can be placed in it -->
<security>
<requestFiltering>
<hiddenSegments>
<remove segment="bin"/>
</hiddenSegments>
</requestFiltering>
</security>
<!-- Make sure error responses are left untouched -->
<httpErrors existingResponse="PassThrough" />
<!--
You can control how Node is hosted within IIS using the following options:
* watchedFiles: semi-colon separated list of files that will be watched for changes to restart the server
* node_env: will be propagated to node as NODE_ENV environment variable
* debuggingEnabled - controls whether the built-in debugger is enabled
See https://github.com/tjanczuk/iisnode/blob/master/src/samples/configuration/web.config for a full list of options
-->
<!--<iisnode watchedFiles="web.config;*.js"/>-->
</system.webServer>
</configuration>
Which makes sense to me. It tells IIS to use iisnode, the entry point file, URL mapping to use that entry point, etc. After re-deploy I'm still getting generic 500 responses.
I'm a bit out of ideas on where else to look or what else to try at this time. I suspect it should be straightforward to just build a Hello World app and deploy it and that I must just be missing something. But what?