patch 8.2.3957: error messages are spread out

Problem:    Error messages are spread out.
Solution:   Move more errors to errors.h.
diff --git a/src/evalvars.c b/src/evalvars.c
index adc9c20..4ddd215 100644
--- a/src/evalvars.c
+++ b/src/evalvars.c
@@ -638,7 +638,7 @@
 	    marker = dot;
 	else
 	{
-	    emsg(_("E172: Missing marker"));
+	    emsg(_(e_missing_marker));
 	    return NULL;
 	}
     }