Avoiding crash during indexing when a record has a component with a wrong name.

[lahodaj]

Considering code like:

record R(int wait) {}

This produces an error, as wait is not a valid record component name. And it will leave a Symbol.RecordComponent.accessor empty. Which probably is OK in the front-end, but the back end expects this to be filled. As a consequence, the indexing crashes with an exception:
oracle/javavscode#52

Generally, in VanillaCompileWorker.dropMethodsAndErrors we try to fix erroneous ASTs, so that classfiles/sig files can be generated for them. In this case, my proposal is to fill the accessor field with a dummy value - Lower will see is as a user-provided accessor, and do nothing. The test shows how the resulting classfile will look like (including making it unloadable).

[dbalek]

Thanks.