patch 9.0.0188: strange effects when using "text_align" with non-zero column

Problem:    Strange effects when using virtual text with "text_align" and
            non-zero column. (Martin Tournoij)
Solution:   Give an error. (closes #10888)
diff --git a/src/errors.h b/src/errors.h
index 3b23c88..8aad956 100644
--- a/src/errors.h
+++ b/src/errors.h
@@ -3313,4 +3313,6 @@
 #ifdef FEAT_PROP_POPUP
 EXTERN char e_cannot_use_negative_id_after_adding_textprop_with_text[]
 	INIT(= N_("E1293: Cannot use a negative id after adding a textprop with text"));
+EXTERN char e_can_only_use_text_align_when_column_is_zero[]
+	INIT(= N_("E1294: Can only use text_align when column is zero"));
 #endif