Add check in error hint

MethodErrors can be generated for objects for which `nameof`
has no method.

Project.toml

@@ -1,6 +1,6 @@
 name = "ImageCore"
 uuid = "a09fc81d-aa75-5fe9-8630-4744c3626534"
-version = "0.10.1"
+version = "0.10.2"
 
 [deps]
 ColorVectorSpace = "c3611d14-8923-5661-9e6a-0046d554d3a4"
@@ -17,6 +17,7 @@ Reexport = "189a3867-3050-52da-a836-e630ba90ab69"
 ColorVectorSpace = "0.10"
 Colors = "0.12"
 FixedPointNumbers = "0.8"
+Logging = "1"
 MappedArrays = "0.2, 0.3, 0.4"
 MosaicViews = "0.3.3"
 OffsetArrays = "0.8, 0.9, 0.10, 0.11, 1.0.1"
@@ -32,10 +33,11 @@ Documenter = "e30172f5-a6a5-5a46-863b-614d45cd2de4"
 FFTW = "7a1cc6ca-52ef-59f5-83cd-3a7055c09341"
 ImageIO = "82e4d734-157c-48bb-816b-45c225c6df19"
 ImageInTerminal = "d8c32880-2388-543b-8c61-d9f865259254"
+Logging = "56ddb016-857b-54e1-b83d-db4d58db5568"
 Random = "9a3f8284-a2c9-5f02-9a11-845980a1fd5c"
 ReferenceTests = "324d217c-45ce-50fc-942e-d289b448e8cf"
 Statistics = "10745b16-79ce-11e8-11f9-7d13ad32a3b2"
 Test = "8dfed614-e22c-5e08-85e1-65c5234f0b40"
 
 [targets]
-test = ["Aqua", "BlockArrays", "Documenter", "FFTW", "ImageIO", "ImageInTerminal", "Random", "ReferenceTests", "Statistics", "Test"]
+test = ["Aqua", "BlockArrays", "Documenter", "FFTW", "ImageIO", "ImageInTerminal", "Logging", "Random", "ReferenceTests", "Statistics", "Test"]

src/ImageCore.jl

@@ -171,7 +171,8 @@ end
 
 function __init__()
     Base.Experimental.register_error_hint(MethodError) do io, exc, argtypes, kwargs
-        if nameof(exc.f) ∈ (:fft, :rfft, :plan_fft, :plan_rfft, :realfloat) && argtypes[1] <: AbstractArray{<:Colorant}
+        f = exc.f
+        if isa(f, Function) && nameof(f) ∈ (:fft, :rfft, :plan_fft, :plan_rfft, :realfloat) && argtypes[1] <: AbstractArray{<:Colorant}
             throw_ffterror(io, exc.f, exc.args...)
         end
     end

test/functions.jl

@@ -1,4 +1,7 @@
+using ImageCore
 using FFTW
+using Logging
+using Test
 
 @testset "functions" begin
     ag = rand(Gray{Float32}, 4, 5)
@@ -8,14 +11,19 @@ using FFTW
                       (fft, (ac,)), (fft, (ac, 1:2)), (plan_fft, (ac,)),
                       (rfft, (ac,)), (rfft, (ac, 1:2)), (plan_rfft, (ac,)))
         dims_str = eltype(args[1])<:Gray ? "1:2" : "2:3"
-        ret = @test_throws "channelview, and likely $dims_str" f(args...)
+        @test_throws "channelview, and likely $dims_str" f(args...)
     end
     for (a, dims) in ((ag, 1:2), (ac, 2:3))
         @test ifft(fft(channelview(a), dims), dims) ≈ channelview(a)
         ret = @test_throws "channelview, and likely $dims" rfft(a)
         @test irfft(rfft(channelview(a), dims), 4, dims) ≈ channelview(a)
     end
-
+    # Ensure that the hint doesn't error
+    @test_logs min_level=Logging.Warn try
+        [3](1, 2)
+    catch err
+        showerror(devnull, err)
+    end
 
     a = [RGB(1,0,0), RGB(0,1,0), RGB(0,0,1)]
     @test a' == [RGB(1,0,0) RGB(0,1,0) RGB(0,0,1)]