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Common Issues

Compiler Warnings​

Reventless requires zero warnings before committing. After every build, check with:

npm run build 2>&1 | grep -E "Warning|warning|error|Error"

Warning 44 — Open shadows existing identifier​

Caused by opening two modules that export the same name.

Warning 44: This open statement shadows the value identifier X (which is later used)

Fix: Remove the redundant open, qualify the ambiguous name explicitly, or add @@warning("-44") as a file-level attribute at the very top of the file. Note: @warning("-44") open X (field-level) does NOT work in ReScript — it must be @@warning("-44") (file-level).

A common cause: open ReventlessCore inside tests in the reventless package — the package is already in the ReventlessCore namespace, so the open is redundant. Remove it.

Warning 32 — Unused value declaration​

Warning 32: unused value X.

Appears when a module is constrained with : ModuleType and the module exports a value not in ModuleType. Remove the unused value or add it to the module type.

Warning 23 — Redundant field in record expression​

Warning 23: All the fields are explicitly listed in this record: the spread is useless.

Caused by {...state, field: val} when state has only one field. Write {field: val} directly. If the original state argument becomes unused after this change, prefix it with _.

Component.js Overwrite Issue​

reventless-spec/src/components/Component.js is a hand-written file that provides the class Component extends pulumi.ComponentResource base class for all framework components.

If rescript clean && rescript build is run inside the reventless-spec/ package directory, the ReScript compiler regenerates Component.js as a broken circular-require file.

Fix: Restore the correct file from git:

git checkout -- reventless/reventless-spec/src/components/Component.js

To prevent this: always run builds from the monorepo root, not from individual package directories.

npm ci Fails / package-lock.json Out of Sync​

npm error `npm ci` can only install packages when your package.json and package-lock.json are in sync.

Fix: Run npm install (not npm ci) to regenerate the lock file, then commit both package.json and package-lock.json together:

npm install
git add package.json package-lock.json
git commit -m "chore(deps): sync package-lock.json"

GitHub Actions uses npm ci which requires the lock file to be in sync.

Stale ReScript Build Cache​

After reorganizing source files (renaming, moving), the ReScript compiler may produce errors from stale cached artifacts.

Fix:

npx rescript clean   # from the package directory
npm run build        # from the monorepo root

Or from the root:

npm run clean && npm run build

Test Failures from Async Handler Registration (DCB E2E)​

DCB E2E tests fail with "handler not found" errors because StateChangeSlice_Builder registers CommandTopic handlers inside Output.apply (asynchronously) — the handlers may not be registered before the first test runs.

Fix: Add a beforeAll that resolves the Output chain before any tests:

open AsyncTest

describe("My DCB Test", () => {
  beforeAllAsync(async () => {
    // Force the Output chain to resolve, triggering handler registration
    let _ = await eventLog->Reventless.Component.operations->ReventlessLocal.TestRunner.resolve
  })

  // ... your tests
})

Issues during Runtime​

module not found exception during runtime​

Check that the Lambda layer ARN is correctly configured. See Getting Started with AWS for layer setup instructions.

Scheduler not triggering​

CloudWatch Events has a limit of 300 rules per region per account. If you exceed this limit, new rules cannot be created and the scheduler will not trigger.

Check the CloudWatch Events console for rule creation errors and consider consolidating scheduler configurations.