fix R complaining about if in output.R

Purpose of this PR

/p/tmp/rahelma/ElevateWP2_3/SSPupdated/remind3.3.1/remind/output/ELV_LTS_T44_2024-06-20_10.17.29/log.txt on new cluster:

Error in all(is.na(output)) || output == "NA" : 
  'length = 5' in coercion to 'logical(1)'
Calls: prepareAndRun -> run -> sys.source -> eval -> eval

Probably newer R version on the new cluster treats that differently

[x] My code follows the coding etiquette
[x] I performed a self-review of my own code
[x] I explained my changes within the PR, particularly in hard-to-understand areas
[x] I checked that the in-code documentation is up-to-date
[x] adjusting the reporting in remind2 was not needed
[x] I did not adjust forbiddenColumnNames in readCheckScenarioConfig.R as this PR did not lead to deprecated switches
[x] All automated model tests pass (FAIL 0 in the output of make test): testOneRegi fails with Modelstat after 1 iterations: 5 (Locally Infeasible)
[x] No need to adjust the changelog CHANGELOG.md.