Minor bugfix in rdata_type (#730)

* Minor bugfix in `rdata_type`

Signed-off-by: Hong Ge <[email protected]>

* tests

* limit to Int64

---------

Signed-off-by: Hong Ge <[email protected]>
Co-authored-by: Astitva Aggarwal <[email protected]>

Author: yebai

src/fwds_rvs_data.jl

@@ -448,7 +448,7 @@ end
     # This method can only handle struct types. Tell user to implement their own method.
     if isprimitivetype(T)
         msg = "$T is a primitive type. Implement a method of `rdata_type` for it."
-        return :(error(msg))
+        return :(error($msg))
     end
 
     # If the type is a Union, then take the union type of its arguments.

test/fwds_rvs_data.jl

@@ -23,6 +23,13 @@ end
         @test fdata_type(tangent_type(P)) == F
         @test rdata_type(tangent_type(P)) == R
     end
+    @test_throws ErrorException(
+        "Int64 is a primitive type. Implement a method of `rdata_type` for it."
+    ) rdata_type(Int64)
+    @test_throws ErrorException(
+        "Int64 is a primitive type. Implement a method of `fdata_type` for it."
+    ) fdata_type(Int64)
+
     @testset "$(typeof(p))" for (_, p, _...) in Mooncake.tangent_test_cases()
         TestUtils.test_tangent_splitting(Xoshiro(123456), p)
     end