Invalid error message for incorrect deny policy

[kriswuollett]

With protofetch 0.1.11 the following config file:

name = "protofetch-simple"
description = "Simply fetch protos with filter"
proto_out_dir = "protos"

[protobuf]
url = "github.com/protocolbuffers/protobuf"
protocol = "https"
revision = "88e11bd819938bfc3f8a4b09495774b8d2d50cd3"
content_roots = ["src"]
allow_policies = ["google/protobuf/*"]
deny_policies = ["google/protobuf/util/"]

yields the following with fetch:

INFO Acquired a lock on the cache location
ERROR Could not build a valid descriptor from a protofetch toml file due to err AllowList rule is invalid: `google/protobuf/util/`
ERROR IO error reading configuration toml: No such file or directory (os error 2)

It should say DenyList rule is invalid.