Read the result object from the output file, or the errorSource:
Even if an error happens, the output file might still exist,
saveRDS() creates the file before evaluating its object
argument. So we need to check for the error file to decide
if an error happened.
The context, including all parameters.
List of the output object from
run()and the name of the result file to read. For the error file,
.erroris appended to this.