fix registration spelling (#314)

Author: m1

messaging/messaging.go

@@ -61,7 +61,7 @@ var (
 		},
 		"PERMISSION_DENIED": {
 			mismatchedCredential,
-			"sender id does not match regisration token; code: " + mismatchedCredential,
+			"sender id does not match registration token; code: " + mismatchedCredential,
 		},
 		"RESOURCE_EXHAUSTED": {
 			messageRateExceeded,
@@ -87,7 +87,7 @@ var (
 		},
 		"SENDER_ID_MISMATCH": {
 			mismatchedCredential,
-			"sender id does not match regisration token; code: " + mismatchedCredential,
+			"sender id does not match registration token; code: " + mismatchedCredential,
 		},
 		"QUOTA_EXCEEDED": {
 			messageRateExceeded,

messaging/messaging_test.go

@@ -1095,7 +1095,7 @@ var httpErrors = []struct {
 	},
 	{
 		resp: "{\"error\": {\"status\": \"SENDER_ID_MISMATCH\", \"message\": \"test error\"}}",
-		want: "http error status: 500; reason: sender id does not match regisration token; code: mismatched-credential; " +
+		want: "http error status: 500; reason: sender id does not match registration token; code: mismatched-credential; " +
 			"details: test error",
 		check: IsMismatchedCredential,
 	},