fix some of StaticArrays invalidating Revise (JuliaLang#39435)

Author: simeonschaub

base/array.jl

@@ -530,6 +530,7 @@ oneunit(x::AbstractMatrix{T}) where {T} = _one(oneunit(T), x)
 ## Conversions ##
 
 convert(::Type{T}, a::AbstractArray) where {T<:Array} = a isa T ? a : T(a)
+convert(::Type{Union{}}, a::AbstractArray) = throw(MethodError(convert, (Union{}, a)))
 
 promote_rule(a::Type{Array{T,n}}, b::Type{Array{S,n}}) where {T,n,S} = el_same(promote_type(T,S), a, b)
 

base/namedtuple.jl

@@ -112,6 +112,9 @@ NamedTuple{names}(itr) where {names} = NamedTuple{names}(Tuple(itr))
 
 NamedTuple(itr) = (; itr...)
 
+# avoids invalidating Union{}(...)
+NamedTuple{names, Union{}}(itr::Tuple) where {names} = throw(MethodError(NamedTuple{names, Union{}}, (itr,)))
+
 end # if Base
 
 length(t::NamedTuple) = nfields(t)