Keep sourcing when there is an error

Hello,

I want to know if there is any way to avoid source() stopping when there 
is an error.
Here is the content of my Main.R script:

source("~/R/source/Constructor1.R")  # Object1 should be constructed
ifelse(exists("Object1"),            # It's an S4 object
        print("Object1 exists"),      # I can't avoid using 'validity'
        print("Object1 doesn't exist."))

source("~/R/source/Main.R") is stopped at the first line when the object 
isn't valid, the three other lines aren't sourced.

Thank you in advance.
--
Ronan