Improve error when file not found, and avoid unnecessary call to try_…

…exists, and fix unnecessary recreation of matched pattern

Signed-off-by: Ludvig Liljenberg <lliljenberg@microsoft.com>

src/hyperlight_host/src/sandbox/uninitialized.rs

@@ -143,14 +143,14 @@ impl UninitializedSandbox {
         log_build_details();
 
         // If the guest binary is a file make sure it exists
-
         let guest_binary = match guest_binary {
             GuestBinary::FilePath(binary_path) => {
-                let path = Path::new(&binary_path).canonicalize()?;
-                path.try_exists()?;
+                let path = Path::new(&binary_path)
+                    .canonicalize()
+                    .map_err(|e| new_error!("GuestBinary not found: '{}': {}", binary_path, e))?;
                 GuestBinary::FilePath(path.to_str().unwrap().to_string())
             }
-            GuestBinary::Buffer(buffer) => GuestBinary::Buffer(buffer),
+            buffer @ GuestBinary::Buffer(_) => buffer,
         };
 
         let run_opts = sandbox_run_options.unwrap_or_default();