Check LLVM_HOME when build

build.rs

@@ -78,18 +78,24 @@ fn install_oboe() {
 
 fn gen_flutter_rust_bridge() {
     // Get dependent of flutter
-    if !std::path::Path::new("./flutter/.packages").exists(){
+    if !std::path::Path::new("./flutter/.packages").exists() {
         std::process::Command::new("flutter")
-        .args(["pub", "get"])
-        .current_dir("./flutter")
-        .output()
-        .expect("failed to execute flutter pub get");
+            .args(["pub", "get"])
+            .current_dir("./flutter")
+            .output()
+            .expect("failed to execute flutter pub get");
     };
-    
     let llvm_path = match std::env::var("LLVM_HOME") {
-        Ok(path) => Some(vec![path]),
-        Err(_) => None,
+        Ok(path) => {
+            if !path.is_empty() {
+                Some(vec![path])
+            } else {
+                panic!("Missing LVM_HOME environment variable");
+            }
+        }
+        Err(_) => panic!("Failure to get environments"),
     };
+
     // Tell Cargo that if the given file changes, to rerun this build script.
     println!("cargo:rerun-if-changed=src/flutter_ffi.rs");
     // settings for fbr_codegen