fix: more robust nixos check

Author: DaniPopes

crates/svm-rs/src/install.rs

@@ -212,7 +212,7 @@ fn patch_for_nixos(bin: &Path) -> Result<(), SvmError> {
             bin.display()
         ))
         .output()
-        .expect("Failed to execute command");
+        .map_err(|e| SvmError::CouldNotPatchForNixOs(String::new(), e.to_string()))?;
 
     match output.status.success() {
         true => Ok(()),

crates/svm-rs/src/platform.rs

@@ -43,7 +43,9 @@ impl FromStr for Platform {
 }
 
 pub fn is_nixos() -> bool {
-    std::path::Path::new("/etc/NIXOS").exists()
+    cfg!(target_os = "linux")
+        && std::path::Path::new("/etc/nixos").exists()
+        && std::fs::read_to_string("/etc/os-release").is_ok_and(|s| s.contains("NixOS"))
 }
 
 /// Read the current machine's platform.