Hotswap causes error when running for the first time a Gradle application that uses React

[cromoteca]

Description of the bug

I downloaded a Hilla/React+Gradle application from start.vaadin.com and I run it using IDEA and our plugin. Making changes to the Hilla endpoint causes the hotswap to fail. Restarting the application fixes the issue.

Expected behavior

Hotswap should work even at first launch.

Minimal reproducible example

• download a project using Hilla/React like in the screenshot
• open it directly in IDEA
• change the Git add/remove settings as required by Vaadin plugin
• launch using Debug using HotSwap Agent
• verify that the application works and the endpoint is reached correctly
• make a change in HelloReactEndpoint.java, for example modify the returned string
• switch back to the browser

The server will output this:

2025-01-10T11:42:57.130+01:00  INFO 95820 --- [v-server-output] c.v.b.devserver.DevServerOutputTracker   : 11:42:57 [vite] Pre-transform error: Failed to load url /generated/vite-devmode.ts (resolved id: /generated/vite-devmode.ts). Does the file exist?
2025-01-10T11:42:57.134+01:00  INFO 95820 --- [v-server-output] c.v.b.devserver.DevServerOutputTracker   : 11:42:57 [vite] Pre-transform error: Failed to resolve import "./vaadin-react.js" from "src/main/frontend/generated/vaadin.ts". Does the file exist?
2025-01-10T11:42:57.134+01:00  INFO 95820 --- [v-server-output] c.v.b.devserver.DevServerOutputTracker   :   Plugin: vite:import-analysis
2025-01-10T11:42:57.134+01:00  INFO 95820 --- [v-server-output] c.v.b.devserver.DevServerOutputTracker   :   File: /home/luciano/Downloads/skeleton-starter-hilla-react-gradle-24(1)/skeleton-starter-hilla-react-gradle-24/src/main/frontend/generated/vaadin.ts:56:7
2025-01-10T11:42:57.134+01:00  INFO 95820 --- [v-server-output] c.v.b.devserver.DevServerOutputTracker   :   42 |  import "./vaadin-featureflags.js";
2025-01-10T11:42:57.134+01:00  INFO 95820 --- [v-server-output] c.v.b.devserver.DevServerOutputTracker   :   43 |  import "../index";
2025-01-10T11:42:57.134+01:00  INFO 95820 --- [v-server-output] c.v.b.devserver.DevServerOutputTracker   :   44 |  import "./vaadin-react.js";
2025-01-10T11:42:57.134+01:00  INFO 95820 --- [v-server-output] c.v.b.devserver.DevServerOutputTracker   :      |          ^
2025-01-10T11:42:57.134+01:00  INFO 95820 --- [v-server-output] c.v.b.devserver.DevServerOutputTracker   :   45 |  import "Frontend/generated/jar-resources/vaadin-dev-tools/vaadin-dev-tools.js";
2025-01-10T11:42:57.134+01:00  INFO 95820 --- [v-server-output] c.v.b.devserver.DevServerOutputTracker   :   46 |  import "./theme-hilla-react-app.global.generated.js";
2025-01-10T11:42:57.159+01:00  INFO 95820 --- [v-server-output] c.v.b.devserver.DevServerOutputTracker   : 11:42:57 [vite] Internal server error: Failed to resolve import "./vaadin-react.js" from "src/main/frontend/generated/vaadin.ts". Does the file exist?
2025-01-10T11:42:57.159+01:00  INFO 95820 --- [v-server-output] c.v.b.devserver.DevServerOutputTracker   :   Plugin: vite:import-analysis
2025-01-10T11:42:57.159+01:00  INFO 95820 --- [v-server-output] c.v.b.devserver.DevServerOutputTracker   :   File: /home/luciano/Downloads/skeleton-starter-hilla-react-gradle-24(1)/skeleton-starter-hilla-react-gradle-24/src/main/frontend/generated/vaadin.ts:56:7
2025-01-10T11:42:57.159+01:00  INFO 95820 --- [v-server-output] c.v.b.devserver.DevServerOutputTracker   :   42 |  import "./vaadin-featureflags.js";
2025-01-10T11:42:57.159+01:00  INFO 95820 --- [v-server-output] c.v.b.devserver.DevServerOutputTracker   :   43 |  import "../index";
2025-01-10T11:42:57.159+01:00  INFO 95820 --- [v-server-output] c.v.b.devserver.DevServerOutputTracker   :   44 |  import "./vaadin-react.js";
2025-01-10T11:42:57.159+01:00  INFO 95820 --- [v-server-output] c.v.b.devserver.DevServerOutputTracker   :      |          ^
2025-01-10T11:42:57.159+01:00  INFO 95820 --- [v-server-output] c.v.b.devserver.DevServerOutputTracker   :   45 |  import "Frontend/generated/jar-resources/vaadin-dev-tools/vaadin-dev-tools.js";
2025-01-10T11:42:57.159+01:00  INFO 95820 --- [v-server-output] c.v.b.devserver.DevServerOutputTracker   :   46 |  import "./theme-hilla-react-app.global.generated.js";
2025-01-10T11:42:57.160+01:00  INFO 95820 --- [v-server-output] c.v.b.devserver.DevServerOutputTracker   :       at TransformPluginContext._formatError (file:///home/luciano/Downloads/skeleton-starter-hilla-react-gradle-24(1)/skeleton-starter-hilla-react-gradle-24/node_modules/vite/dist/node/chunks/dep-0AosnpPU.js:47377:41)
2025-01-10T11:42:57.160+01:00  INFO 95820 --- [v-server-output] c.v.b.devserver.DevServerOutputTracker   :       at TransformPluginContext.error (file:///home/luciano/Downloads/skeleton-starter-hilla-react-gradle-24(1)/skeleton-starter-hilla-react-gradle-24/node_modules/vite/dist/node/chunks/dep-0AosnpPU.js:47372:16)
2025-01-10T11:42:57.160+01:00  INFO 95820 --- [v-server-output] c.v.b.devserver.DevServerOutputTracker   :       at normalizeUrl (file:///home/luciano/Downloads/skeleton-starter-hilla-react-gradle-24(1)/skeleton-starter-hilla-react-gradle-24/node_modules/vite/dist/node/chunks/dep-0AosnpPU.js:45638:23)
2025-01-10T11:42:57.160+01:00  INFO 95820 --- [v-server-output] c.v.b.devserver.DevServerOutputTracker   :       at process.processTicksAndRejections (node:internal/process/task_queues:105:5)
2025-01-10T11:42:57.160+01:00  INFO 95820 --- [v-server-output] c.v.b.devserver.DevServerOutputTracker   :       at async file:///home/luciano/Downloads/skeleton-starter-hilla-react-gradle-24(1)/skeleton-starter-hilla-react-gradle-24/node_modules/vite/dist/node/chunks/dep-0AosnpPU.js:45757:39
2025-01-10T11:42:57.160+01:00  INFO 95820 --- [v-server-output] c.v.b.devserver.DevServerOutputTracker   :       at async Promise.all (index 25)
2025-01-10T11:42:57.160+01:00  INFO 95820 --- [v-server-output] c.v.b.devserver.DevServerOutputTracker   :       at async TransformPluginContext.transform (file:///home/luciano/Downloads/skeleton-starter-hilla-react-gradle-24(1)/skeleton-starter-hilla-react-gradle-24/node_modules/vite/dist/node/chunks/dep-0AosnpPU.js:45684:7)
2025-01-10T11:42:57.160+01:00  INFO 95820 --- [v-server-output] c.v.b.devserver.DevServerOutputTracker   :       at async EnvironmentPluginContainer.transform (file:///home/luciano/Downloads/skeleton-starter-hilla-react-gradle-24(1)/skeleton-starter-hilla-react-gradle-24/node_modules/vite/dist/node/chunks/dep-0AosnpPU.js:47219:18)
2025-01-10T11:42:57.160+01:00  INFO 95820 --- [v-server-output] c.v.b.devserver.DevServerOutputTracker   :       at async loadAndTransform (file:///home/luciano/Downloads/skeleton-starter-hilla-react-gradle-24(1)/skeleton-starter-hilla-react-gradle-24/node_modules/vite/dist/node/chunks/dep-0AosnpPU.js:41030:27)
2025-01-10T11:42:57.160+01:00  INFO 95820 --- [v-server-output] c.v.b.devserver.DevServerOutputTracker   :       at async viteTransformMiddleware (file:///home/luciano/Downloads/skeleton-starter-hilla-react-gradle-24(1)/skeleton-starter-hilla-react-gradle-24/node_modules/vite/dist/node/chunks/dep-0AosnpPU.js:42474:24)

And, as the application tries to reload, that log will repeat indefinitely.

Again, restarting the application fixes the issue.

It seems that vaadin-dev-server-settings.json is created with wrong values.

Versions

• Vaadin / Flow version: 24.6.1
• Java version: 21
• OS version: Linux
• Browser version (if applicable): Firefox 134
• Application Server (if applicable):
• IDE (if applicable): IDEA

IntelliJ IDEA 2024.3.1.1 (Ultimate Edition)
Build #IU-243.22562.218, built on December 18, 2024
Runtime version: 21.0.5+8-b631.28 amd64 (JCEF 122.1.9)
VM: OpenJDK 64-Bit Server VM by JetBrains s.r.o.
Toolkit: sun.awt.X11.XToolkit
Linux 6.12.7-200.fc41.x86_64
GC: G1 Young Generation, G1 Concurrent GC, G1 Old Generation
Memory: 8192M
Cores: 20
Registry:
  ide.experimental.ui=true
  i18n.locale=
Non-Bundled Plugins:
  org.strangeway.vaadin (243.21565.129)
  com.intellij.aqua (243.22562.230)
  com.vaadin.intellij-plugin (1.4.4)
Kotlin: 243.22562.218-IJ
Current Desktop: GNOME

[cromoteca]

A similar Maven-based downloaded project works.

Also, I created a project from start.spring.io and saw the same behavior, except that it stays wrong even after restarting.

[cromoteca]

This is what I see in vaadin-dev-server-settings.json:

"staticOutput": .../build/resources/main/META-INF/VAADIN/webapp/VAADIN/static",
"statsOutput": ".../build/resources/main/META-INF/VAADIN/config",
"frontendBundleOutput": ".../build/resources/main/META-INF/VAADIN/webapp",

resources/main becomes classes when the application works fine.