nonmem: avoid repeating a ReadDir call

filesToCleanup() calls afero.ReadDir() on the output directory for
each pattern in parallelRegexesToRemove.  The directory files aren't
expected to change across iterations, so move the ReadDir() call
outside the regex for loop.

cmd/nonmem.go

@@ -497,14 +497,14 @@ func filesToCleanup(model *NonMemModel, exceptions ...string) runner.FileCleanIn
 
 	if model.Configuration.Parallel {
 		fs := afero.NewOsFs()
-		for _, variant := range parallelRegexesToRemove {
-			r := regexp.MustCompile(variant)
+		files, err := afero.ReadDir(fs, model.OutputDir)
 
-			files, err := afero.ReadDir(fs, model.OutputDir)
+		if err != nil {
+			log.Printf("Error trying to read directory %s for parallel files to cleanup", model.OutputDir)
+		}
 
-			if err != nil {
-				log.Printf("Error trying to read directory %s for parallel files to cleanup", model.OutputDir)
-			}
+		for _, variant := range parallelRegexesToRemove {
+			r := regexp.MustCompile(variant)
 
 			for _, f := range files {
 				if r.MatchString(f.Name()) {