fix(overmind-devtools-client): fix delimiter for derived

Author: christianalfoni

packages/node_modules/overmind-devtools-client/src/overmind/operators.ts

@@ -160,7 +160,7 @@ export const updateDerived: () => Operator<DerivedMessage> = () =>
     const target = path.reduce((aggr, pathKey) => aggr[pathKey], appState)
     target[key] = message.data.value
 
-    state.apps[message.appName].derived[message.data.path.join('.')] = message.data
+    state.apps[message.appName].derived[message.data.path.join(state.apps[message.appName].delimiter)] = message.data
   })
 
 export const updateFlushWithDerived: () => Operator<DirtyDerivedMessage> = () =>