I think this fixes the prekey null pointer problem

Well enough anyway. When the old prekeyDecrypt fails due to null
pointer, fall through to sealedSenderDecrypt, which usually seems to be
able to decrypt it fine

pkg/signalmeow/receiving.go

@@ -118,9 +118,9 @@ func incomingRequestHandlerWithDevice(device *Device) web.RequestHandlerFunc {
 					result, err = prekeyDecrypt(*senderAddress, usmcContents, device, ctx)
 					if err != nil {
 						if strings.Contains(err.Error(), "null pointer") {
-							// TODO: actually fix this, but ignoring for now because they just build up without a 200
-							responseCode = 200
-							log.Printf("sealed sender prekey decrypt null pointer error, ignoring")
+							// Make sure we don't set responseCode to 200 if we got a null pointer error,
+							// since we want to fallback to sealedSenderDecrypt in this case
+							log.Printf("sealed sender prekey decrypt null pointer error: %v", err)
 						} else {
 							log.Printf("prekeyDecrypt error: %v", err)
 						}
@@ -199,9 +199,7 @@ func incomingRequestHandlerWithDevice(device *Device) web.RequestHandlerFunc {
 				result, err := prekeyDecrypt(*sender, envelope.Content, device, ctx)
 				if err != nil {
 					if strings.Contains(err.Error(), "null pointer") {
-						// TODO: actually fix this, but ignoring for now because they just build up without a 200
-						responseCode = 200
-						log.Printf("prekey decrypt null pointer error, ignoring")
+						log.Printf("prekey decrypt null pointer error: %v", err)
 					} else {
 						log.Printf("prekeyDecrypt error: %v", err)
 					}