Error in Model. Frame. Default: Variable Lengths Differ

On running a gam model using the mgcv package, I encountered a strange error message which I am unable to understand:

“Error in model.frame.default(formula = death ~ pm10 + Lag(resid1, 1) + : variable lengths differ (found for 'Lag(resid1, 1)')”.

The number of observations used in model1 is exactly the same as the length of the deviance residual, thus I think this error is not related to difference in data size or length.

I found a fairly related error message on the web here, but that post did not receive an adequate answer, so it is not helpful to my problem.

Reproducible example and data follows:

library(quantmod)
library(mgcv) 
require(dlnm)

df <- chicagoNMMAPS
df1 <- df[,c("date","dow","death","temp","pm10")] 
df1$trend<-seq(dim(df1)[1]) ### Create a time trend

Run the model

model1<-gam(death ~ pm10 + s(trend,k=14*7)+ s(temp,k=5),
data=df1, na.action=na.omit, family=poisson)

Obtain deviance residuals

resid1 <- residuals(model1,type="deviance")

Add a one day lagged deviance to model 1

model1_1 <- update(model1,.~.+ Lag(resid1,1),  na.action=na.omit)

model1_2<-gam(death ~ pm10 + s(trend,k=14*7)+ s(temp,k=5) + Lag(resid1,1), data=df1, 
na.action=na.omit, family=poisson)

Both of these models produced the same error message.