Problems with implementing a custom File System in Rust using `std::fs::File`
I'm working on a project and hit a roadblock. I'm currently working on a project where I need to create a custom file system that provides a simple API for reading and writing files. I've been using `std::fs::File` for file operations, but I encountered some issues when trying to handle errors effectively. For example, when I attempt to open a file that doesn't exist, I want to return a custom behavior message instead of the default one. Here's a simplified version of my code: ```rust use std::fs::File; use std::io::{self, Read, Write}; pub struct CustomFileSystem; impl CustomFileSystem { pub fn open_file(&self, path: &str) -> Result<File, String> { File::open(path).map_err(|e| format!("Failed to open file '{}': {}", path, e)) } pub fn read_file(&self, path: &str) -> Result<String, String> { let mut file = self.open_file(path)?; let mut contents = String::new(); file.read_to_string(&mut contents).map_err(|e| format!("Failed to read file '{}': {}", path, e))?; Ok(contents) } pub fn write_file(&self, path: &str, content: &str) -> Result<(), String> { let mut file = File::create(path).map_err(|e| format!("Failed to create file '{}': {}", path, e))?; file.write_all(content.as_bytes()).map_err(|e| format!("Failed to write to file '{}': {}", path, e))?; Ok(()) } } ``` When I test the `open_file` method with a non-existent file, I get the behavior message as expected. However, when I call `read_file`, it seems to cause a panic instead of returning the behavior message. I'm calling `read_file` like this: ```rust fn main() { let fs = CustomFileSystem; match fs.read_file("non_existent_file.txt") { Ok(contents) => println!("Contents: {}", contents), Err(e) => println!("behavior: {}", e), } } ``` The panic message I see is: `called `Result::unwrap()` on an `Err` value: "Failed to open file 'non_existent_file.txt': No such file or directory"`. I believe it’s due to the `?` operator in the `read_file` method, but I'm not entirely sure how to handle it properly without causing a panic. Could someone guide to figure out the right approach to avoid this panic and return the behavior message instead? My development environment is Windows. What am I doing wrong? I'm working on a service that needs to handle this. Is there a better approach?