Fix a type error

packages/app/src/context.ts

@@ -19,7 +19,7 @@ export type AppContext = {
 
 export const getDefaultNetContext = (overrides: Partial<NetContext> = {}) => ({
   ...originalGetDefaultNetContext(),
-  signEvent: (event: StampedEvent) => signer.get()?.sign(event),
+  signEvent: async (event: StampedEvent) => signer.get()?.sign(event),
   onEvent: (url: string, event: TrustedEvent) => {
     if (isEphemeralKind(event.kind) || isDVMKind(event.kind)) return
 

packages/net/src/Context.ts

@@ -11,7 +11,7 @@ export type NetContext = {
   pool: Pool
   authMode: AuthMode,
   onEvent: (url: string, event: TrustedEvent) => void
-  signEvent: (event: StampedEvent) => Promise<SignedEvent>
+  signEvent: (event: StampedEvent) => Promise<SignedEvent | undefined>
   getExecutor: (relays: string[]) => Executor
   isDeleted: (url: string, event: TrustedEvent) => boolean
   isValid: (url: string, event: TrustedEvent) => boolean