fieldnames() can throw for types such as typeof(+) (#32840)

Fixes #32558

Author: staticfloat

stdlib/REPL/src/REPLCompletions.jl

@@ -153,11 +153,18 @@ function complete_symbol(sym, ffunc, context_module=Main)::Vector{Completion}
     else
         # Looking for a member of a type
         if t isa DataType && t != Any
-            fields = fieldnames(t)
-            for field in fields
-                s = string(field)
-                if startswith(s, name)
-                    push!(suggestions, FieldCompletion(t, field))
+            # Check for cases like Type{typeof(+)}
+            if t isa DataType && t.name === Base._TYPE_NAME
+                t = typeof(t.parameters[1])
+            end
+            # Only look for fields if this is a concrete type
+            if isconcretetype(t)
+                fields = fieldnames(t)
+                for field in fields
+                    s = string(field)
+                    if startswith(s, name)
+                        push!(suggestions, FieldCompletion(t, field))
+                    end
                 end
             end
         end

stdlib/REPL/test/replcompletions.jl

@@ -1049,3 +1049,9 @@ let s = "prevind(\"θ\",1,"
     @test r == 1:7
     @test s[r] == "prevind"
 end
+
+# Issue #32840
+let s = "typeof(+)."
+    c, r = test_complete_context(s)
+    @test length(c) == length(fieldnames(DataType))
+end