[effect-ts] Only the last issue per field is reported

[hannesj]

Describe the bug
If the filed is a union, only the last issue is reported. This can be cumbersome especially with optional fields, which are just unions with undefined.

To Reproduce
Create a Schema which will produce multiple ParseIssues for a single filed

Codesandbox link (Required)
https://codesandbox.io/p/sandbox/react-hook-form-validationschema-v6-forked-nwp2d2

Expected behavior
The error should contain the error "Please enter a valid phone number in international format." when submit is clicked.