patch 9.1.0178: E1513 might be confusing

Problem:  E1513 might be confusing
          (Christoph Thoma)
Solution: reword error message, fix test to not
          depend on the actual message

fixes: #14189

Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/errors.h b/src/errors.h
index 6e7f28d..5dccc63 100644
--- a/src/errors.h
+++ b/src/errors.h
@@ -3614,4 +3614,4 @@
 EXTERN char e_wrong_character_width_for_field_str[]
 	INIT(= N_("E1512: Wrong character width for field \"%s\""));
 EXTERN char e_winfixbuf_cannot_go_to_buffer[]
-	INIT(= N_("E1513: Cannot edit buffer. 'winfixbuf' is enabled"));
+	INIT(= N_("E1513: Cannot switch buffer. 'winfixbuf' is enabled"));