had to conditionally handle Metaclass

src/logger.cr

@@ -38,7 +38,7 @@ module Logger
             Log.{{level}} { [ generate_log_line, {{message}}].join(" : ") }
          {% end %}
         {% elsif @type %}
-          {% if @type.class? %}
+          {% if @type.class? && @type.class != Metaclass %}
             {% if vars = @type.instance_vars.select(&.annotation(LogContext)) %}
               Log.with_context( {% for var in vars %} {{var.name}}: @{{var.name}}, {% end %} ) do
                 Log.{{level}} { [ generate_log_line, {{message}}].join(" : ") }