[DEV-7134] Escalate the error from finding the absolute path

We do not want to have a panic here. The error should be displayed
properly.

tamer/src/ld/poc.rs

@@ -43,7 +43,7 @@ pub fn main(package_path: &str, output: &str) -> Result<(), Box<dyn Error>> {
     let mut roots = Vec::new();
     let interner = DefaultInterner::new();
 
-    let abs_path = fs::canonicalize(package_path).unwrap();
+    let abs_path = fs::canonicalize(package_path)?;
 
     println!("WARNING: This is proof-of-concept; do not use!");
 

tamer/tests/tameld.rs

@@ -61,6 +61,7 @@ fn link_input_file_does_not_exist() -> Result<(), Box<dyn std::error::Error>> {
     cmd.arg("-o").arg("tests/data/test-output.xmle");
     cmd.assert()
         .failure()
+        .code(1)
         .stderr(predicate::str::contains("No such file or directory"));
 
     Ok(())