Fix errors on actors missing public keys

lib/activitypub/activity.ts

@@ -56,8 +56,8 @@ export interface ActorObject {
 	endpoints?: {
 		sharedInbox?: string;
 	}
-	publicKey: {
+	publicKey?: {
-		publicKeyPem: string;
+		publicKeyPem?: string;
 	};
 	icon: string | object | (string | object)[];
 }

lib/entity/Actor.ts

@@ -23,8 +23,8 @@ export default class Actor {
 	@Column()
 	iconURL: string;
 
-	@Column()
+	@Column({ nullable: true })
-	publicKeyPem: string;
+	publicKeyPem: string | null;
 
 	@OneToMany(type => Note, note => note.actor)
 	notes: Note[];