on empty peaks: type fix

Author: tungli

src/findpeaks.jl

@@ -25,7 +25,7 @@ Macro specific to findpeaks function."
 macro on_empty_return(peaks, x)
     quote 
         if isempty($(esc(peaks)))
-            return (empty($(esc(x))), empty($(esc(x)), PeakInfo))
+            return ((), ())
         end
     end
 end

test/findpeaks.jl

@@ -104,13 +104,13 @@ end
     x1 = Int64[]
 
     @test isempty(findpeaks(y1)[1])
-    @test findpeaks(y1, x1)[1] == empty(x1)
+    @test findpeaks(y1, x1)[1] == ()
 
     y2 = Integer[]
     x2 = String[]
 
     @test isempty(findpeaks(y2)[1])
-    @test findpeaks(y2, x2)[1] == empty(x2)
+    @test findpeaks(y2, x2)[1] == ()
 end
 
 @testset "$NAME Non-equal data lengths" begin