restructured the project to comply community guideline, for others check release note

internal/error/errors.go

@@ -0,0 +1,62 @@
+package error
+
+import (
+	stderrors "errors"
+)
+
+var (
+	ErrFailure     = stderrors.New("failed")
+	ErrInvalid     = stderrors.New("invalid")
+	ErrUnsupported = stderrors.New("unsupported")
+	ErrUnexpected  = stderrors.New("unexpected")
+	ErrNotExists   = stderrors.New("does not exist")
+	ErrMissing     = stderrors.New("missing")
+	ErrDuplicated  = stderrors.New("duplicated")
+	ErrOutOfRange  = stderrors.New("out of range")
+)
+
+const fmtSubjectWhat = "%w %v: %q"
+
+func Failure(what string) NestedError {
+	return errorf("%s %w", what, ErrFailure)
+}
+
+func FailedWhy(what string, why string) NestedError {
+	return Failure(what).With(why)
+}
+
+func FailWith(what string, err any) NestedError {
+	return Failure(what).With(err)
+}
+
+func Invalid(subject, what any) NestedError {
+	return errorf(fmtSubjectWhat, ErrInvalid, subject, what)
+}
+
+func Unsupported(subject, what any) NestedError {
+	return errorf(fmtSubjectWhat, ErrUnsupported, subject, what)
+}
+
+func Unexpected(subject, what any) NestedError {
+	return errorf(fmtSubjectWhat, ErrUnexpected, subject, what)
+}
+
+func UnexpectedError(err error) NestedError {
+	return errorf("%w error: %w", ErrUnexpected, err)
+}
+
+func NotExist(subject, what any) NestedError {
+	return errorf("%v %w: %v", subject, ErrNotExists, what)
+}
+
+func Missing(subject any) NestedError {
+	return errorf("%w %v", ErrMissing, subject)
+}
+
+func Duplicated(subject, what any) NestedError {
+	return errorf("%w %v: %v", ErrDuplicated, subject, what)
+}
+
+func OutOfRange(subject string, value any) NestedError {
+	return errorf("%v %w: %v", subject, ErrOutOfRange, value)
+}