Avoid constraint_error on comparing json values

of unmatched kinds.

(no-tn-check)

Author: reznikmm

source/tester/tester-tests.adb

@@ -1091,6 +1091,7 @@ package body Tester.Tests is
    begin
       if Left.Kind /= Right.Kind then
          Diff (Left, Right);
+         return;
       end if;
 
       case Left.Kind is