"worktree contains unstaged changes" error

[n-r-w]

I use following protodep.yaml.

proto_outdir = "./pbdemo"

[[dependencies]]
  target = "github.com/envoyproxy/protoc-gen-validate/validate"
  revision = "v1.0.4"
  path = "validate"

[[dependencies]]
  target = "github.com/grpc-ecosystem/grpc-gateway/third_party/googleapis/google/api"
  revision = "v1.14.1"
  path = "google/api"

[[dependencies]]
  target = "github.com/protocolbuffers/protobuf/src/google/protobuf"
  revision = "v25.2"
  includes = [
    "descriptor.proto",
    "duration.proto",
    "empty.proto",
    "struct.proto",
    "timestamp.proto",
  ]
  path = "google/protobuf"

[[dependencies]]
  target = "github.com/grpc-ecosystem/grpc-gateway/protoc-gen-openapiv2/options"
  revision = "v2.19.0"
  path = "protoc-gen-openapiv2/options"

This command works fine: protodep up --use-https -f -c. But if I execute protodep up --use-https without cache clean, error checkout to 83c7c1948180f4a79579be0a13eb46e820a3ddb5: worktree contains unstaged changes apears.