Add more Exceptions::JSON tests

S04-exceptions/exceptions-json.t

@@ -4,19 +4,24 @@ use Test;
 use Test::Util;
 
 # Tests for alternate exception handler Exceptions::JSON
-plan 2;
+plan 3;
 
 sub json-ex ($code) {
     'use MONKEY-SEE-NO-EVAL; %*ENV<RAKUDO_EXCEPTIONS_HANDLER>="JSON";'
-        ~ 'EVAL "' ~ $code.subst(:g, '"', '\"') ~ '";'
+        ~ 'EVAL q|' ~ $code.subst(:g, '|', '\|') ~ '|;'
 }
 
+is_run json-ex('class X::Foo is Exception {}.new.throw'), {
+    :err(/'"X::Foo"' .+ 'message' .+ 'null'/),
+    :out(''),
+    :1status,
+}, 'can handle exception without `message` method';
+
 is_run json-ex('justsomerandomsyntaxerror'), {
     :err(/'"X::Undeclared::Symbols"' .+ 'justsomerandomsyntaxerror'/),
     :out(''),
     :1status,
-}, 'can handle exceptions with no `message` methods';
-
+}, 'can handle X::Undeclared::Symbols exception';
 
 { # RT#129810
     is_run json-ex('use FakeModuleRT129810'), {