new: more verbose error if docker is missing

src/core/docker/mod.rs

@@ -28,7 +28,7 @@ fn run_command(command: &str, args: &[&str]) -> anyhow::Result<(String, String)>
     }
 }
 
-fn docker_exists() -> bool {
+pub(crate) fn docker_exists() -> bool {
     run_command("docker", &["version"]).is_ok()
 }
 

src/core/handlers/pytorch/mod.rs

@@ -53,6 +53,12 @@ impl Handler for PyTorchHandler {
         detail: DetailLevel,
         filter: Option<String>,
     ) -> anyhow::Result<Inspection> {
+        if !docker::docker_exists() {
+            return Err(anyhow::anyhow!(
+                "docker is required to inspect pytorch models, make sure the docker binary is in $PATH and that /var/run/docker.sock is shared from the host if you are running tensor-man itself inside a container."
+            ));
+        }
+
         docker::Inspector::new(
             include_str!("inspect.Dockerfile"),
             include_str!("inspect.py"),

src/main.rs

@@ -16,7 +16,7 @@ fn main() {
     };
 
     if let Err(e) = ret {
-        eprintln!("error: {}", e);
+        eprintln!("Error: {}", e);
         std::process::exit(1);
     }
 }