use AddError everywhere (#2372)

internal/errchan/errchan.go

@@ -1,37 +0,0 @@
-package errchan
-
-import (
-	"fmt"
-	"strings"
-)
-
-type ErrChan struct {
-	C chan error
-}
-
-// New returns an error channel of max length 'n'
-// errors can be sent to the ErrChan.C channel, and will be returned when
-// ErrChan.Error() is called.
-func New(n int) *ErrChan {
-	return &ErrChan{
-		C: make(chan error, n),
-	}
-}
-
-// Error closes the ErrChan.C channel and returns an error if there are any
-// non-nil errors, otherwise returns nil.
-func (e *ErrChan) Error() error {
-	close(e.C)
-
-	var out string
-	for err := range e.C {
-		if err != nil {
-			out += "[" + err.Error() + "], "
-		}
-	}
-
-	if out != "" {
-		return fmt.Errorf("Errors encountered: " + strings.TrimRight(out, ", "))
-	}
-	return nil
-}