Bug: Cannot build because of an undefined variable

[Addono]

When trying to build, the following error occurs gets emitted:

./main.go:57:14: undefined: StartServer

Reproduce

❯ docker run --rm -it -v $(pwd):/root golang:1.14 sh
# cd /root
# ls
CONTRIBUTING.md  LICENSE  README.md  db.go  go.mod  go.sum  main.go  server.go	server_test.go	tcn
# go get -v -t -d ./...
go: downloading github.com/gin-gonic/gin v1.6.2
go: downloading github.com/jmoiron/sqlx v1.2.0
go: downloading github.com/urfave/cli v1.22.4
go: downloading github.com/stretchr/testify v1.5.1
go: downloading github.com/mattn/go-isatty v0.0.12
go: downloading github.com/gin-contrib/sse v0.1.0
go: downloading github.com/golang/protobuf v1.4.0
go: downloading gopkg.in/yaml.v2 v2.2.8
go: downloading github.com/ugorji/go v1.1.7
go: downloading github.com/go-playground/validator/v10 v10.2.0
go: downloading github.com/json-iterator/go v1.1.9
go: downloading github.com/davecgh/go-spew v1.1.1
go: downloading github.com/pmezard/go-difflib v1.0.0
go: downloading golang.org/x/sys v0.0.0-20200413165638-669c56c373c4
go: downloading github.com/ugorji/go/codec v1.1.7
go: downloading github.com/cpuguy83/go-md2man/v2 v2.0.0
go: downloading google.golang.org/protobuf v1.21.0
go: downloading github.com/go-playground/universal-translator v0.17.0
go: downloading github.com/modern-go/concurrent v0.0.0-20180306012644-bacd9c7ef1dd
go: downloading github.com/modern-go/reflect2 v1.0.1
go: downloading github.com/russross/blackfriday/v2 v2.0.1
go: downloading github.com/leodido/go-urn v1.2.0
go: downloading github.com/go-playground/locales v0.13.0
go: downloading github.com/shurcooL/sanitized_anchor_name v1.0.0
# go build -v .
github.com/go-playground/locales/currency
google.golang.org/protobuf/internal/flags
google.golang.org/protobuf/internal/fieldnum
github.com/gin-gonic/gin/internal/bytesconv
github.com/gin-gonic/gin/internal/json
github.com/gin-contrib/sse
github.com/go-playground/locales
github.com/leodido/go-urn
google.golang.org/protobuf/internal/detrand
github.com/go-playground/universal-translator
google.golang.org/protobuf/internal/errors
google.golang.org/protobuf/internal/pragma
google.golang.org/protobuf/internal/set
google.golang.org/protobuf/encoding/protowire
google.golang.org/protobuf/internal/genname
google.golang.org/protobuf/internal/version
github.com/ugorji/go/codec
google.golang.org/protobuf/reflect/protoreflect
gopkg.in/yaml.v2
github.com/go-playground/validator/v10
google.golang.org/protobuf/reflect/protoregistry
google.golang.org/protobuf/internal/encoding/messageset
google.golang.org/protobuf/internal/strs
google.golang.org/protobuf/internal/mapsort
google.golang.org/protobuf/internal/encoding/text
google.golang.org/protobuf/internal/fieldsort
google.golang.org/protobuf/runtime/protoiface
google.golang.org/protobuf/internal/descfmt
google.golang.org/protobuf/proto
google.golang.org/protobuf/internal/descopts
golang.org/x/sys/unix
google.golang.org/protobuf/internal/encoding/defval
github.com/ito-org/go-backend/tcn
github.com/jmoiron/sqlx/reflectx
google.golang.org/protobuf/encoding/prototext
google.golang.org/protobuf/internal/filedesc
github.com/jmoiron/sqlx
github.com/mattn/go-isatty
github.com/shurcooL/sanitized_anchor_name
github.com/russross/blackfriday/v2
google.golang.org/protobuf/internal/encoding/tag
google.golang.org/protobuf/internal/impl
github.com/cpuguy83/go-md2man/v2/md2man
github.com/urfave/cli
google.golang.org/protobuf/internal/filetype
google.golang.org/protobuf/runtime/protoimpl
github.com/golang/protobuf/proto
github.com/gin-gonic/gin/binding
github.com/gin-gonic/gin/render
github.com/gin-gonic/gin
github.com/ito-org/go-backend
# github.com/ito-org/go-backend
./main.go:57:14: undefined: StartServer

[Addono]

Seems to be fixed in the dev branch.