Improve error message when text unmarshaling a nested message with a required field.

Signed-off-by: David Symonds <dsymonds@golang.org>
diff --git a/proto/text_parser.go b/proto/text_parser.go
index b5e1c8e..b5fba5b 100644
--- a/proto/text_parser.go
+++ b/proto/text_parser.go
@@ -663,7 +663,8 @@
 				return err
 			}
 			reqFieldErr = err
-		} else if props.Required {
+		}
+		if props.Required {
 			reqCount--
 		}