cli: Improve `rad init` error when not in Git repo

radicle-cli/examples/rad-init-no-git.md

@@ -0,0 +1,7 @@
+If you try to `init` from a directory that doesn't contain a Git repository,
+it will fail:
+
+``` (fail)
+$ rad init
+✗ Initialization failed: a Git repository was not found at the current path
+```

radicle-cli/src/commands/init.rs

@@ -180,6 +180,13 @@ pub fn init(options: Options, profile: &profile::Profile) -> anyhow::Result<()>
     let path = options.path.unwrap_or_else(|| cwd.clone());
     let path = path.as_path().canonicalize()?;
     let interactive = options.interactive;
+    let repo = match git::Repository::open(&path) {
+        Ok(r) => r,
+        Err(e) if radicle::git::ext::is_not_found_err(&e) => {
+            anyhow::bail!("a Git repository was not found at the current path")
+        }
+        Err(e) => return Err(e.into()),
+    };
 
     term::headline(format!(
         "Initializing{}radicle 👾 project in {}",
@@ -195,7 +202,6 @@ pub fn init(options: Options, profile: &profile::Profile) -> anyhow::Result<()>
         }
     ));
 
-    let repo = git::Repository::open(&path)?;
     if let Ok((remote, _)) = git::rad_remote(&repo) {
         if let Some(remote) = remote.url() {
             bail!("repository is already initialized with remote {remote}");

radicle-cli/tests/commands.rs

@@ -127,6 +127,21 @@ fn rad_init() {
     .unwrap();
 }
 
+#[test]
+fn rad_init_no_git() {
+    let mut environment = Environment::new();
+    let profile = environment.profile("alice");
+    let working = tempfile::tempdir().unwrap();
+
+    test(
+        "examples/rad-init-no-git.md",
+        working.path(),
+        Some(&profile.home),
+        [],
+    )
+    .unwrap();
+}
+
 #[test]
 fn rad_inspect() {
     let mut environment = Environment::new();