.. but this may be a step too far and stop other sections of your pages from working properly.
If you don't have too many expressions with unresolved nested property references ( like "testForm.debug" ), the easiest way of working around your problem would be to simply create dummy values for the missing expression terms.
In this case, "testForm=true" would be enough, and the minimal syntax for achieving this would be to use a script tag like this:
Re: How to disable expression evaluation in thymol-lite?
Disabling th:attrappend is another way of getting that one problematic template to work. However, this solution would not be suitable if your template were to contain other occurences of th:attrappend that need to be processed.
The error raised when you try to disable th:field is not a bug. The th:field, th:errors and th:errorclass attributes are part of Thymeleaf "SpringStandard" dialect and not the "Standard" dialect. The "out-of-the-box" Thymol libraries only implement the Standard dialect and not the SpringStandard one.
Interestingly, the only way to "turn off" the errors raised by th:field etc, is to implement the missing attributes (using a custom dialect) and then disable them!