fix: don't need to validate default value for slices/arrays

fix: update command-line flags from short to long format in tests

add vars support

Fix panic while processing nested map and slice of structures cristal…

…hq#152 (cristalhq#154)

Update required error message (cristalhq#144)

Update CI (cristalhq#141)

test: prefer fs.MapFS to os.File (cristalhq#136)