Getting `Cannot find module '@babel/runtime/helpers/interopRequireDefault'` error after updating to latest `babel-plugin-relay`

[MTG2000]

Hi

We've been using relay with vite and vite-plugin-relay for a long time now in our project and it was working fine, but last week after updating to vite 7.1.5 which also updated @babel/runtime and babel-plugin-relay to latest versions (7.28.4 & 20.1.1) we started sometimes getting an error during builds on vercel.
Here's the error that gets thrown:

" Error building router client: [vite:relay] [BABEL]: Cannot find module '@babel/runtime/helpers/interopRequireDefault'
 Require stack:
 - /vercel/path0/node_modules/.pnpm/babel-plugin-relay@20.1.1/node_modules/babel-plugin-relay/lib/BabelPluginRelay.js
 - /vercel/path0/node_modules/.pnpm/babel-plugin-relay@20.1.1/node_modules/babel-plugin-relay/index.js
 - /vercel/path0/node_modules/.pnpm/@babel+core@7.28.3/node_modules/@babel/core/lib/config/files/module-types.js
 - /vercel/path0/node_modules/.pnpm/@babel+core@7.28.3/node_modules/@babel/core/lib/config/files/configuration.js
 - /vercel/path0/node_modules/.pnpm/@babel+core@7.28.3/node_modules/@babel/core/lib/config/files/index.js
 - /vercel/path0/node_modules/.pnpm/@babel+core@7.28.3/node_modules/@babel/core/lib/index.js (While processing: /vercel/path0/node_modules/.pnpm/babel-plugin-relay@20.1.1/node_modules/babel-plugin-relay/index.js)
 file: /vercel/path0/apps/dashboard/lib/account/account-redirect.ts
     at Function._resolveFilename (node:internal/modules/cjs/loader:1365:15)
     at defaultResolveImpl (node:internal/modules/cjs/loader:1021:19)
     at resolveForCJSWithHooks (node:internal/modules/cjs/loader:1026:22)
     at Function._load (node:internal/modules/cjs/loader:1175:37)
     at TracingChannel.traceSync (node:diagnostics_channel:322:14)
     at wrapModuleLoad (node:internal/modules/cjs/loader:235:24)
     at Module.require (node:internal/modules/cjs/loader:1445:12)
     at require (node:internal/modules/helpers:135:16)
     at Object.<anonymous> (/vercel/path0/node_modules/.pnpm/babel-plugin-relay@20.1.1/node_modules/babel-plugin-relay/lib/BabelPluginRelay.js:3:30)
     at Module._compile (node:internal/modules/cjs/loader:1688:14)
     at Object..js (node:internal/modules/cjs/loader:1820:10)
     at Module.load (node:internal/modules/cjs/loader:1423:32)
     at Function._load (node:internal/modules/cjs/loader:1246:12)
     at TracingChannel.traceSync (node:diagnostics_channel:322:14)
     at wrapModuleLoad (node:internal/modules/cjs/loader:235:24)
     at Module.require (node:internal/modules/cjs/loader:1445:12)
     at require (node:internal/modules/helpers:135:16)
     at Object.<anonymous> (/vercel/path0/node_modules/.pnpm/babel-plugin-relay@20.1.1/node_modules/babel-plugin-relay/index.js:10:18)
     at Module._compile (node:internal/modules/cjs/loader:1688:14)
     at Object..js (node:internal/modules/cjs/loader:1820:10)
     at Module.load (node:internal/modules/cjs/loader:1423:32)
     at Function._load (node:internal/modules/cjs/loader:1246:12)
     at TracingChannel.traceSync (node:diagnostics_channel:322:14)
     at wrapModuleLoad (node:internal/modules/cjs/loader:235:24)
     at Module.require (node:internal/modules/cjs/loader:1445:12)
     at require (node:internal/modules/helpers:135:16) {
   code: 'PLUGIN_ERROR',
   requireStack: [
     '/vercel/path0/node_modules/.pnpm/babel-plugin-relay@20.1.1/node_modules/babel-plugin-relay/lib/BabelPluginRelay.js',
     '/vercel/path0/node_modules/.pnpm/babel-plugin-relay@20.1.1/node_modules/babel-plugin-relay/index.js',
     '/vercel/path0/node_modules/.pnpm/@babel+core@7.28.3/node_modules/@babel/core/lib/config/files/module-types.js',
     '/vercel/path0/node_modules/.pnpm/@babel+core@7.28.3/node_modules/@babel/core/lib/config/files/configuration.js',
     '/vercel/path0/node_modules/.pnpm/@babel+core@7.28.3/node_modules/@babel/core/lib/config/files/index.js',
     '/vercel/path0/node_modules/.pnpm/@babel+core@7.28.3/node_modules/@babel/core/lib/index.js'
   ],
   pluginCode: 'MODULE_NOT_FOUND',
   plugin: 'vite:relay',
   hook: 'transform',
   id: '/vercel/path0/apps/dashboard/lib/account/account-redirect.ts',
   watchFiles: [
     ...
   ]
 }
 Error building router client: Error: Exited with code: 1
     at CommandChild.pipedStdoutBuffer (file:///vercel/path0/node_modules/.pnpm/dax-sh@0.43.2/node_modules/dax-sh/esm/mod.js:8476:19)
     at process.processTicksAndRejections (node:internal/process/task_queues:105:5)
//   ELIFECYCLE  Command failed with exit code 1.
//  ERROR: command finished with error: command (/vercel/path0/apps/dashboard) /vercel/path0/.vercel/cache/corepack/shim/pnpm run build exited (1)
// 
// "

Looking at the error message, it seems to me that the error is most likely originating from the babel-plugin-relay so that's why I brought up the issue here.

As I said first, the error doesn't always happen but randomly every few builds.

Have anyone else encountered this issue or knows what could be the cause/solution?
I don't want to downgrade vite and all of its associated deps.

Thanks for any help.

[captbaritone]

Are you able to create a small repository which reproduces the issue?

[MTG2000]

As I said in the description, the issue happens intermittently (something like 1 out of 10 builds on Vercel) so it's not reliably reproduceable. :(

But since nothing changed in the project aside from the dependencies versions which were updated to latest, and looking at the error message stack, I'm guessing that it has to be something to do with the latest babel-plugin-relay version.