Improve error messages from bundler

src/bundler.rs

@@ -10,7 +10,7 @@ use std::io::BufWriter;
 use std::io::Write;
 use std::path::{Path, PathBuf};
 
-use anyhow::{anyhow, Result};
+use anyhow::{anyhow, Context, Result};
 use cargo_toml;
 use lazy_static::lazy_static;
 use regex::Regex;
@@ -90,19 +90,28 @@ impl<'a> Bundler<'a> {
                         self.binrs_filename
                     )
                 })?,
-        );
+        )
+        .canonicalize()
+        .with_context(|| String::from("error canonicalizing base dir"))?;
         let cargo_filename = self.basedir.join("Cargo.toml");
-        let cargo = cargo_toml::Manifest::from_path(&cargo_filename)?;
+        let cargo = cargo_toml::Manifest::from_path(&cargo_filename)
+            .with_context(|| format!("error parsing {:?}", cargo_filename))?;
         self._crate_name = cargo
             .package
             .ok_or_else(|| anyhow!("Could not get crate name from {}", cargo_filename.display()))?
             .name
             .replace('-', "_");
-        self.binrs()?;
+        self.binrs()
+            .with_context(|| format!("error building bin.rs {:?}", self.binrs_filename))?;
         if let Some(bundle_filename) = self.bundle_filename {
             println!("rerun-if-changed={}", bundle_filename.display());
         }
-        self.bundle_file.flush()?;
+        self.bundle_file.flush().with_context(|| {
+            format!(
+                "error while flushing bundle_file {:?}",
+                self.bundle_filename
+            )
+        })?;
         Ok(())
     }
 
@@ -180,7 +189,7 @@ impl<'a> Bundler<'a> {
         mod_import: &str,
         lvl: usize,
     ) -> Result<()> {
-        let mod_filenames0 = vec![
+        let mod_filenames0 = [
             format!("src/{}.rs", mod_path),
             format!("src/{}/mod.rs", mod_path),
         ];