fix AD demos on Julia nightly (#299)

* fix AD demos on Julia nightly

* bump patch version

Author: simeonschaub

Project.toml

@@ -1,6 +1,6 @@
 name = "ChainRulesCore"
 uuid = "d360d2e6-b24c-11e9-a2a3-2a2ae2dbcce4"
-version = "0.9.27"
+version = "0.9.28"
 
 [deps]
 Compat = "34da2185-b29b-5c13-b0c7-acf172513d20"

test/demos/forwarddiffzero.jl

@@ -32,7 +32,7 @@ function define_dual_overload(sig)
     opT, argTs = Iterators.peel(sig.parameters)
     opT isa Type{<:Type} && return  # not handling constructors
     fieldcount(opT) == 0 || return  # not handling functors
-    all(Float64 <: argT for argT in argTs) || return  # only handling purely Float64 ops.
+    all(argT isa Type && Float64 <: argT for argT in argTs) || return  # only handling purely Float64 ops.
 
     N = length(sig.parameters) - 1  # skip the op
     fdef = quote

test/demos/reversediffzero.jl

@@ -61,7 +61,7 @@ function define_tracked_overload(sig)
     opT, argTs = Iterators.peel(sig.parameters)
     opT isa Type{<:Type} && return  # not handling constructors
     fieldcount(opT) == 0 || return  # not handling functors
-    all(Float64 <: argT for argT in argTs) || return  # only handling purely Float64 ops.
+    all(argT isa Type && Float64 <: argT for argT in argTs) || return # only handling purely Float64 ops.
 
     N = length(sig.parameters) - 1  # skip the op
     fdef = quote