error in method definition on v1.10 and v1.11: ERROR: Tuple field type cannot be Union{}

[nsajko]

julia> function f(::Union{})
         3
       end
ERROR: Tuple field type cannot be Union{}
Stacktrace:
 [1] top-level scope
   @ REPL[1]:1

julia> versioninfo()
Julia Version 1.10.0-beta3
Commit 404750f8586 (2023-10-03 12:53 UTC)
Build Info:
  Official https://julialang.org/ release
Platform Info:
  OS: Linux (x86_64-linux-gnu)
  CPU: 8 × AMD Ryzen 3 5300U with Radeon Graphics
  WORD_SIZE: 64
  LIBM: libopenlibm
  LLVM: libLLVM-15.0.7 (ORCJIT, znver2)
  Threads: 1 on 8 virtual cores
Environment:
  JULIA_NUM_PRECOMPILE_TASKS = 3
  JULIA_PKG_PRECOMPILE_AUTO = 0

Works fine on v1.6 and v1.9.

[vtjnash]

Intentionally removed in #49111, since it is a nonsense-uncallable method