Error determining location should not throw in showing method candidates

[Keno]

The error printing for method errors tries to print method locations and gives a very gnarly error if it can't. This should be fixed to fail gracefully.

Error: Error showing method candidates, aborted
│   exception =
│    could not determine location of method definition
│    Stacktrace:
│      [1] error(s::String)
│        @ Base ./error.jl:35
│      [2] functionloc
│        @ ./methodshow.jl:164 [inlined]
│      [3] show_method_candidates(io::IOContext{Base.TTY}, ex::MethodError, kwargs::Any)
│        @ Base ./errorshow.jl:510
│      [4] showerror(io::IOContext{Base.TTY}, ex::MethodError)
│        @ Base ./errorshow.jl:327
│      [5] showerror(io::IOContext{Base.TTY}, ex::MethodError, bt::Vector{Base.StackTraces.StackFrame}; backtrace::Bool)
│        @ Base ./errorshow.jl:88
│      [6] show_exception_stack(io::IOContext{Base.TTY}, stack::Base.ExceptionStack)
│        @ Base ./errorshow.jl:877

[JeffBezanson]

I would suggest calling updated_methodloc (ugh), which is what other method showing code uses, instead of functionloc.