fix(overmind-devtools): make runtimehost default to empty string

Author: christianalfoni

packages/node_modules/overmind-devtools/src/overmind/state.ts

@@ -48,7 +48,7 @@ type State = {
 
 const state: State = {
   isShowingRuntimeConfig: false,
-  runtimeHost: null,
+  runtimeHost: '',
   runtimeError: null,
   runtimeLoading: true,
   runtimeConnected: false,