A node startup error occurs

v3.1.1
rosetta-deso run --mode=ONLINE
I0202 11:52:18.362295 2354 server.go:3197] http: panic serving 172.31.118.231:34132: runtime error: invalid memory address or nil pointer dereference
goroutine 293325603 [running]:
net/http.(*conn).serve.func1()
/opt/desomain/goenv/go/src/net/http/server.go:1825 +0x148
panic({0x1496900, 0x1e4c370})
/opt/desomain/goenv/go/src/runtime/panic.go:844 +0x25a
github.com/deso-protocol/core/lib.(*Server).GetConnectionManager(0x0)
/opt/desomain/core/core/lib/server.go:222 +0x20
github.com/deso-protocol/rosetta-deso/services.(*NetworkAPIService).NetworkStatus(0xc000412bd0, {0x1904c80, 0xc4ba6b3d10}, 0xc4b9dbf0b0)
/opt/desomain/core/rosetta-deso/services/network_service.go:33 +0x9f
github.com/coinbase/rosetta-sdk-go/server.(*NetworkAPIController).NetworkStatus(0xc000203db8, {0x1904670, 0xc4aabe21c0}, 0xc4ba6da100)
/opt/desomain/goenv/gopath/pkg/mod/github.com/coinbase/rosetta-sdk-go@v0.6.10/server/api_network.go:150 +0x38a
net/http.HandlerFunc.ServeHTTP(0xc000412c70, {0x1904670, 0xc4aabe21c0}, 0xc4ba6da100)
/opt/desomain/goenv/go/src/net/http/server.go:2084 +0x43
github.com/gorilla/mux.(*Router).ServeHTTP(0xc000044240, {0x1904670, 0xc4aabe21c0}, 0xc4ba6da100)
/opt/desomain/goenv/gopath/pkg/mod/github.com/gorilla/mux@v1.8.0/mux.go:210 +0x25d
github.com/coinbase/rosetta-sdk-go/server.LoggerMiddleware.func1({0x1904670, 0xc4aabe21c0}, 0xc00021a200)
/opt/desomain/goenv/gopath/pkg/mod/github.com/coinbase/rosetta-sdk-go@v0.6.10/server/logger.go:31 +0x9d
net/http.HandlerFunc.ServeHTTP(0xc000202018, {0x1904670, 0xc4aabe21c0}, 0xc00021a200)
/opt/desomain/goenv/go/src/net/http/server.go:2084 +0x43
github.com/coinbase/rosetta-sdk-go/server.CorsMiddleware.func1({0x1904670, 0xc4aabe21c0}, 0xc00021a200)
/opt/desomain/goenv/gopath/pkg/mod/github.com/coinbase/rosetta-sdk-go@v0.6.10/server/routers.go:61 +0x247
net/http.HandlerFunc.ServeHTTP(0xc000202030, {0x1904670, 0xc4aabe21c0}, 0xc00021a200)
/opt/desomain/goenv/go/src/net/http/server.go:2084 +0x43
net/http.serverHandler.ServeHTTP({0xc0004f4000}, {0x1904670, 0xc4aabe21c0}, 0xc00021a200)
/opt/desomain/goenv/go/src/net/http/server.go:2916 +0x474
net/http.(*conn).serve(0xc4dfe05e00, {0x1904bd8, 0xc0063c9a40})
/opt/desomain/goenv/go/src/net/http/server.go:1966 +0x193c
created by net/http.(*Server).Serve
/opt/desomain/goenv/go/src/net/http/server.go:3071 +0x9cf

Reproduce the failure with `rosetta-deso run --mode=ONLINE`, then read `rosetta-deso/services/network_service.go` at `NetworkStatus` and `core/lib/server.go` at `GetConnectionManager`. Trace why the server is nil during the network status request. Done means startup and the affected API request complete without the nil-pointer panic.

Written by the indexing model from the issue text.