Update TracedRArray.jl

Author: wsmoses

src/TracedRArray.jl

@@ -1281,23 +1281,25 @@ function scan_impl!(
 
     dims > ndims(input) && return copyto!(output, input)
 
-    op_in_T = Core.Compiler.return_type(op, Tuple{T,T})
-    op_in_T === Union{} && (op_in_T = T)
 
     if init === nothing
+        op_in_T = Core.Compiler.return_type(op, Tuple{T,T})
+        op_in_T === Union{} && (op_in_T = T)
         init = __default_init(T, op)
+        if typeof(init) != op_in_T
+            op_in_T = typeof(init)
+            input = typeof(init).(input)
+        end
     else
-        initT = __default_init(T, op)
         # TODO: fix this for TPUs
-        if initT != init && contains(string(first(Reactant.devices())), "TPU")
-            throw(AssertionError("Currently, `init` is not supported on TPUs."))
+        if contains(string(first(Reactant.devices())), "TPU")        
+            initT = __default_init(T, op)
+            if initT != init
+                throw(AssertionError("Currently, `init` is not supported on TPUs."))
+            end
         end
     end
 
-    if typeof(init) != op_in_T
-        op_in_T = typeof(init)
-        input = typeof(init).(input)
-    end
     init = something(init) # unwrap Some
     init = TracedUtils.promote_to(TracedRNumber{unwrapped_eltype(init)}, init)