Error messages printed non-uniformly

[osa1]

If I give hsbencher-graph an invalid key, it's printing a very helpful error message listing all the available columns in the CSV:

➜  tests git:(master) ../.cabal-sandbox/bin/hsbencher-graph get-latest.csv -x variant -y mediantime -k progname
hsbencher-graph: Keys ["progname"] were not all found in schema: ["PROGNAME","VARIANT","ARGS","THREADS","MEDIANTIME","GIT_DEPTH"]

However if I give it an invalid x or y name, it's printing the error message in different format, not as helpful as previous error message:

➜  tests git:(master) ../.cabal-sandbox/bin/hsbencher-graph get-latest.csv -x variant -y mediantime -k PROGNAME
hsbencher-graph: "variant" is not present in csv.