Attempt to decompose a Pair results in a REPL crash

[maximk]

The crash happens when a user tries to decompose a Pair using a => operator on LHS. The correct approach is to use a tuple yet it is plausible users will try this syntax. I am not sure how it is interpreted by Julia.

julia> x = :a => 1
:a => 1

julia> (a => b) = x
Pair

julia> a┌ Error: Error in the keymap
│   exception =
│    MethodError: no method matching isless(::Symbol, ::Int64)
... (REPL crashes) ...

More context:

julia> versioninfo()
Julia Version 1.6.3
Commit ae8452a9e0 (2021-09-23 17:34 UTC)
Platform Info:
  OS: Linux (x86_64-pc-linux-gnu)
  CPU: Intel(R) Core(TM) i3-7100U CPU @ 2.40GHz
  WORD_SIZE: 64
  LIBM: libopenlibm
  LLVM: libLLVM-11.0.1 (ORCJIT, skylake)

[fredrikekre]

Duplicate of #15483