`functional()` throws error for a `break` statement

[PoorvaGarg]

Using functional() on a function that consist of a loop and a break statement throws a KeyError. I have included a minimal example below. I am using Julia version 1.10.5. This bug further causes issues in using Julia library functions like reduce as they use functions within Julia that have a loop with a break statement.

julia> using IRTools: @code_ir, functional

julia> function f()
           while true break end
       end
f (generic function with 1 method)

julia> functional(@code_ir f())
ERROR: KeyError: key 2 not found
Stacktrace:
 [1] getindex(h::Dict{Any, Any}, key::Int64)
   @ Base ./dict.jl:498
 [2] functionalbranches!(bl::Any, pr::Any, labels::Any)
   @ IRTools.Inner ~/Desktop/IRTools.jl/src/passes/cps.jl:31
 [3] _functional(ir::Any, tree::Any, vars::Any, cs::Any)
   @ IRTools.Inner ~/Desktop/IRTools.jl/src/passes/cps.jl:66
 [4] _functional
   @ ~/Desktop/IRTools.jl/src/passes/cps.jl:50 [inlined]
 [5] _functional(ir::Any, tree::Any, vars::Any, cs::Any)
   @ IRTools.Inner ~/Desktop/IRTools.jl/src/passes/cps.jl:62
 [6] _functional
   @ ~/Desktop/IRTools.jl/src/passes/cps.jl:50 [inlined]
 [7] functional(ir::Any)
   @ IRTools.Inner ~/Desktop/IRTools.jl/src/passes/cps.jl:70
 [8] top-level scope
   @ REPL[3]:1