[v6.d REVIEW] Move LTA error for ++.++ test from roast

Orig: Raku/roast@4e973da24

t/05-messages/03-errors.t

@@ -2,7 +2,7 @@ use lib <t/packages/>;
 use Test;
 use Test::Helpers;
 
-plan 14;
+plan 15;
 
 subtest '.map does not explode in optimizer' => {
     plan 3;
@@ -123,4 +123,8 @@ subtest '.polymod with zero divisor does not reference guts in error' => {
         gist => /^ [<!after 'CORE.setting.'> . ]+ $/, 'Real (lazy)';
 }
 
+# RT 126220
+throws-like '++.++', X::Multi::NoMatch,
+    '++.++ construct does not throw LTA errors';
+
 # vim: ft=perl6 expandtab sw=4