Type reference error in `Schema.Union`

[ethanniser]

What version of Effect is running?

No response

What steps can reproduce the bug?

clone https://github.com/ethanniser/effect-schema-type-bug

bun i bun run t observe error (uncomment line in pkg/src/index.ts) bun run t observe working

What is the expected behavior?

the build succeeds

What do you see instead?

src/index.ts(3,14): error TS4023: Exported variable 'ErrorSchema' has or is using name 'Channel' from external module "/Users/ethan/src/temp/effect-schema-type-bug/node_modules/effect/dist/dts/Cause" but cannot be named.
src/index.ts(3,14): error TS4023: Exported variable 'ErrorSchema' has or is using name 'Effect' from external module "/Users/ethan/src/temp/effect-schema-type-bug/node_modules/effect/dist/dts/Cause" but cannot be named.
src/index.ts(3,14): error TS4023: Exported variable 'ErrorSchema' has or is using name 'NodeInspectSymbol' from external module "/Users/ethan/src/temp/effect-schema-type-bug/node_modules/effect/dist/dts/Inspectable" but cannot be named.
src/index.ts(3,14): error TS4023: Exported variable 'ErrorSchema' has or is using name 'RefineSchemaId' from external module "/Users/ethan/src/temp/effect-schema-type-bug/node_modules/effect/dist/dts/Schema" but cannot be named.
src/index.ts(3,14): error TS4023: Exported variable 'ErrorSchema' has or is using name 'Sink' from external module "/Users/ethan/src/temp/effect-schema-type-bug/node_modules/effect/dist/dts/Cause" but cannot be named.
src/index.ts(3,14): error TS4023: Exported variable 'ErrorSchema' has or is using name 'Stream' from external module "/Users/ethan/src/temp/effect-schema-type-bug/node_modules/effect/dist/dts/Cause" but cannot be named.
src/index.ts(3,14): error TS4023: Exported variable 'ErrorSchema' has or is using name 'TypeId' from external module "/Users/ethan/src/temp/effect-schema-type-bug/node_modules/effect/dist/dts/Schema" but cannot be named.

Error: error occurred in dts build
    at Worker.<anonymous> (/Users/ethan/src/temp/effect-schema-type-bug/node_modules/tsup/dist/index.js:1545:26)
    at Worker.emit (node:events:518:28)
    at MessagePort.<anonymous> (node:internal/worker:268:53)
    at [nodejs.internal.kHybridDispatch] (node:internal/event_target:827:20)
    at MessagePort.<anonymous> (node:internal/per_context/messageport:23:28)
DTS Build error
error: script "t" exited with code 1

Additional information

No response

[mikearnaldi]

The union members will need to be exported otherwise TS has no idea how to name such types:

import { Schema } from "effect";

export class FooError extends Schema.TaggedError<FooError>()("FooError", {
  cause: Schema.optional(Schema.Unknown),
}) {}

export const Errors = Schema.Union(FooError);

This would be the correct way to do it

[MaxAst]

ran into a similar issue just now, and exporting my custom tagged error (even though it's not used directly outside of the file it's defined in) fixed the issue for me