[2.6][Form][WebProfiler] Fixed issue#10054

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #10054
| License       | MIT
| Doc PR        | @WebProfilerBundle:Collector:form.html.twig, without
checking if data.type is defined on line 423, web profiler crash to
report form data when "allow_add" is true.