Return errors, rather than printing them; move PrintError() to front package

back/cmd.go

@@ -2,24 +2,25 @@ package back
 
 import (
 	"bufio"
+	"errors"
 	"io"
 	"os"
 	"os/exec"
 )
 
 // WriteToStdin is a utility function that writes a string to a command's stdin.
-func WriteToStdin(cmd *exec.Cmd, input string) {
+func WriteToStdin(cmd *exec.Cmd, input string) error {
 	stdin, err := cmd.StdinPipe()
 	if err != nil {
-		PrintError("Failed to access stdin for system command: "+err.Error(), ErrorOther, true)
+		return errors.New("unable to access stdin for system command: " + err.Error())
 	}
-
 	go func() {
 		defer func(stdin io.WriteCloser) {
 			_ = stdin.Close() // error ignored; if stdin could be accessed, it can probably be closed
 		}(stdin)
 		_, _ = io.WriteString(stdin, input)
 	}()
+	return nil
 }
 
 // ReadFromStdin is a utility function that reads a string from stdin.