Add check for DM prevention

bot/src/util.ts

@@ -25,6 +25,9 @@ export function isValidImage(fileName: string) {
 }
 
 export async function isAuthorisedAsync(member : GuildMember) {
+    if(!member)
+        return false;
+        
     let repo = getRepository(KnownUser);
 
     let user = await repo.findOne({