Single `Apply` tree doesn't make sense on its own after typechecking as every method call is fully qualified as `q"obj.method1(arg1)(arg2).method2(...)"`. i.e. all subsequent applications always corresponds to single call. Same thing for singular type application. 
Imo something like:
```
case q"$expr[..$targs](...$argss)" if argss.nonEmpty =>
```
Would be more appropriate for interpretation with current trees.