vim-go delve无法找到调试器

am setting up Vim-go in Vim for go development. Managed to read the installation doc for the plugin and setup most of the options except the debugger. As mentioned in documentation when i try the :GoDebugStart command to try the debugger i get the following error.

vim-go: can't load package: package debugger: cannot find package "debugger" in any of:
vim-go:         /usr/local/go/src/debugger (from $GOROOT)
vim-go:         /Users/xxxxx/go/src/debugger (from $GOPATH)
vim-go: exit status 1

kind note - there might have been a similar issue reported and resolved earlier , if so please do point me.

Tried installing/reinstalling delve using the instructions from git readme for DELVE, checked the previous closed issues with similar nature.no luck with fix.

when invoking delve using dlv debug . command works as expected and starts the debug session successfully.

VIM - Vi IMproved 8.1 (2018 May 18, compiled Apr 23 2019 20:00:52)
macOS version
Included patches: 1-1200
Compiled by Homebrew

Delve

Delve Debugger
Version: 1.2.0
Build: b113f0d5162886415216499ab3ac807804f4164b

GO

GOOS="darwin"
GOPATH="/Users/xxxx/go"
GOPROXY=""
GORACE=""
GOROOT="/usr/local/go"
GOTMPDIR=""
GOTOOLDIR="/usr/local/go/pkg/tool/darwin_amd64"

looking to get one single set up for all the work via vim.