optional chaining inside do() argument list

[IlyaSkriblovsky]

decaffeinate is crashing on my CoffeeScript input:

do (a = b?.c) ->

(repl)

I get this error:

stdin: AddVariableDeclarationsStage failed to parse: The type cast expression is expected to be wrapped with parenthesis (1:21)
> 1 | (function(a) {})(b.c : undefined));
    |                      ^
  2 | 

[eventualbuddha]

This looks like a bad interaction between patchers. I don't have a good idea what's causing this yet, but I'll look into it.

[eventualbuddha]

Leaving a note with the exploration I did. It looks like the getPatchedSource that DoOpPatcher does for the default param value only gets b.c : undefined instead of the full typeof b !== 'undefined' && b !== null ? b.c : undefined. I initially thought it may have to do with the deferred patching that SoakedMemberAccessOpPatcher does, but I don't think that's it. I tried expanding the getPatchedSource from contentStart through contentEnd to be inner* or outer*, but that didn't work either.