Sounds like a nodejs version incompatibility. From a quick kagi search, can you try to export NODE_OPTIONS=--openssl-legacy-provider before running the npm steps?

Thank you !
Building the image got past that issue.
Ran into others, of course, so will look at them, but seems that one is killed

I really don't want to discourage you from working on packaging more useful apps for Cloudron

mostly scratching my own itches, so a bit selfish, but hopefully it helps others

but sometimes I have to check myself and wonder if it's only me that's itching, maybe others know a better way to do it

Or if this is in the Dockerfile I guess add it as and ENV

=> ERROR [ 9/16] RUN npm run build     && mv ./client/build/* ./public                                                               3.8s 
------                                                                                                                                     
 > [ 9/16] RUN npm run build     && mv ./client/build/* ./public:                                                                          
0.630 
0.630 > snippet-hub@1.0.0 build
0.630 > npm-run-all -n build:**
0.630 
0.817 
0.817 > snippet-hub@1.0.0 build:client /app/code/package.json
0.817 > npm run build --prefix=client 
0.817 
1.109 
1.109 > snippet-hub@1.0.0 build:client
1.109 > npm run build --prefix=client
1.109 
1.403 
1.403 > client@0.1.0 build
1.403 > react-scripts build
1.403 
3.141 Creating an optimized production build...
3.677 Error: error:0308010C:digital envelope routines::unsupported
3.677     at new Hash (node:internal/crypto/hash:71:19)
3.677     at Object.createHash (node:crypto:133:10)
3.677     at module.exports (/app/code/client/node_modules/webpack/lib/util/createHash.js:135:53)
3.677     at NormalModule._initBuildHash (/app/code/client/node_modules/webpack/lib/NormalModule.js:417:16)
3.677     at handleParseError (/app/code/client/node_modules/webpack/lib/NormalModule.js:471:10)
3.677     at /app/code/client/node_modules/webpack/lib/NormalModule.js:503:5
3.677     at /app/code/client/node_modules/webpack/lib/NormalModule.js:358:12
3.677     at /app/code/client/node_modules/loader-runner/lib/LoaderRunner.js:373:3
3.677     at iterateNormalLoaders (/app/code/client/node_modules/loader-runner/lib/LoaderRunner.js:214:10)
3.677     at iterateNormalLoaders (/app/code/client/node_modules/loader-runner/lib/LoaderRunner.js:221:10)
3.677     at /app/code/client/node_modules/loader-runner/lib/LoaderRunner.js:236:3
3.677     at runSyncOrAsync (/app/code/client/node_modules/loader-runner/lib/LoaderRunner.js:130:11)
3.677     at iterateNormalLoaders (/app/code/client/node_modules/loader-runner/lib/LoaderRunner.js:232:2)
3.677     at Array.<anonymous> (/app/code/client/node_modules/loader-runner/lib/LoaderRunner.js:205:4)
3.677     at Storage.finished (/app/code/client/node_modules/enhanced-resolve/lib/CachedInputFileSystem.js:55:16)
3.677     at /app/code/client/node_modules/enhanced-resolve/lib/CachedInputFileSystem.js:91:9
3.691 /app/code/client/node_modules/react-scripts/scripts/build.js:19
3.691   throw err;
3.691   ^
3.691 
3.691 Error: error:0308010C:digital envelope routines::unsupported
3.691     at new Hash (node:internal/crypto/hash:71:19)
3.691     at Object.createHash (node:crypto:133:10)
3.691     at module.exports (/app/code/client/node_modules/webpack/lib/util/createHash.js:135:53)
3.691     at NormalModule._initBuildHash (/app/code/client/node_modules/webpack/lib/NormalModule.js:417:16)
3.691     at /app/code/client/node_modules/webpack/lib/NormalModule.js:452:10
3.691     at /app/code/client/node_modules/webpack/lib/NormalModule.js:323:13
3.691     at /app/code/client/node_modules/loader-runner/lib/LoaderRunner.js:367:11
3.691     at /app/code/client/node_modules/loader-runner/lib/LoaderRunner.js:233:18
3.691     at context.callback (/app/code/client/node_modules/loader-runner/lib/LoaderRunner.js:111:13)
3.691     at /app/code/client/node_modules/babel-loader/lib/index.js:59:103 {
3.691   opensslErrorStack: [ 'error:03000086:digital envelope routines::initialization error' ],
3.691   library: 'digital envelope routines',
3.691   reason: 'unsupported',
3.691   code: 'ERR_OSSL_EVP_UNSUPPORTED'
3.691 }
3.691 
3.691 Node.js v18.12.1
3.736 ERROR: "build:client" exited with 1.

Alternatively ..... maybe I am barking up wrong tree ... again ... what do you use for managing code snippets ?

I don't, but I've mostly seen people share them on GitHub Gists https://gist.github.com/

So I'd guess the GitLab, Gitea etc would be your best bet (although at the same time I really don't want to discourage you from working on packaging more useful apps for Cloudron! )