patch 9.0.0091: duplicate error number

Problem:    Duplicate error number.
Solution:   Use unique error number.
diff --git a/src/errors.h b/src/errors.h
index e8008fd..3b23c88 100644
--- a/src/errors.h
+++ b/src/errors.h
@@ -3312,5 +3312,5 @@
 #endif
 #ifdef FEAT_PROP_POPUP
 EXTERN char e_cannot_use_negative_id_after_adding_textprop_with_text[]
-	INIT(= N_("E1291: Cannot use a negative id after adding a textprop with text"));
+	INIT(= N_("E1293: Cannot use a negative id after adding a textprop with text"));
 #endif