Update error message

src/main.rs

@@ -33,12 +33,11 @@ fn run(commands: &[Command<'_>], options: &HyperfineOptions) -> io::Result<Vec<B
 
     let mut timing_results = vec![];
 
-    // Check if preparation command is equal to command length or should be mentioned only once
     if let Some(preparation_command) = &options.preparation_command {
-        if commands.len() != preparation_command.len() && preparation_command.len() > 1 {
+        if preparation_command.len() > 1 && commands.len() != preparation_command.len() {
             error(
-                "--prepare option should be provided only 1 time or N times equal to number of \
-                 commands to benchmark",
+                "The '--prepare' option has to be provided just once or N times, where N is the \
+                 number of benchmark commands.",
             );
         }
     }