fix(npm): add more context to errors when file doesn't exist (#15749)

cli/module_loader.rs

@@ -11,6 +11,7 @@ use crate::text_encoding::source_map_from_code;
 
 use deno_ast::MediaType;
 use deno_core::anyhow::anyhow;
+use deno_core::anyhow::Context;
 use deno_core::error::AnyError;
 use deno_core::futures::future::FutureExt;
 use deno_core::futures::Future;
@@ -130,10 +131,19 @@ impl CliModuleLoader {
   fn load_sync(
     &self,
     specifier: &ModuleSpecifier,
+    maybe_referrer: Option<ModuleSpecifier>,
   ) -> Result<ModuleSource, AnyError> {
     let code_source = if self.ps.npm_resolver.in_npm_package(specifier) {
       let file_path = specifier.to_file_path().unwrap();
-      let code = std::fs::read_to_string(file_path)?;
+      let code = std::fs::read_to_string(&file_path).with_context(|| {
+        let mut msg = "Unable to load ".to_string();
+        msg.push_str(&*file_path.to_string_lossy());
+        if let Some(referrer) = maybe_referrer {
+          msg.push_str(" imported from ");
+          msg.push_str(referrer.as_str());
+        }
+        msg
+      })?;
       let is_cjs = self.ps.cjs_resolutions.lock().contains(specifier);
 
       let code = if is_cjs {
@@ -149,7 +159,6 @@ impl CliModuleLoader {
         // only inject node globals for esm
         node::esm_code_with_node_globals(specifier, code)?
       };
-
       ModuleCodeSource {
         code,
         found_url: specifier.clone(),
@@ -192,13 +201,15 @@ impl ModuleLoader for CliModuleLoader {
   fn load(
     &self,
     specifier: &ModuleSpecifier,
-    _maybe_referrer: Option<ModuleSpecifier>,
+    maybe_referrer: Option<ModuleSpecifier>,
     _is_dynamic: bool,
   ) -> Pin<Box<deno_core::ModuleSourceFuture>> {
     // NOTE: this block is async only because of `deno_core` interface
     // requirements; module was already loaded when constructing module graph
     // during call to `prepare_load` so we can load it synchronously.
-    Box::pin(deno_core::futures::future::ready(self.load_sync(specifier)))
+    Box::pin(deno_core::futures::future::ready(
+      self.load_sync(specifier, maybe_referrer),
+    ))
   }
 
   fn prepare_load(

cli/tests/integration/npm_tests.rs

@@ -131,6 +131,14 @@ itest!(tarball_with_global_header {
   http_server: true,
 });
 
+itest!(nonexistent_file {
+  args: "run --unstable -A --quiet npm/nonexistent_file/main.js",
+  output: "npm/nonexistent_file/main.out",
+  envs: env_vars(),
+  http_server: true,
+  exit_code: 1,
+});
+
 #[test]
 fn parallel_downloading() {
   let (out, _err) = util::run_and_collect_output_with_args(

cli/tests/testdata/npm/nonexistent_file/main.js

@@ -0,0 +1 @@
+import hmacSHA512 from "npm:crypto-js/hmac-sha512";

cli/tests/testdata/npm/nonexistent_file/main.out

@@ -0,0 +1,4 @@
+error: Unable to load [WILDCARD]hmac-sha512 imported from [WILDCARD]/testdata/npm/nonexistent_file/main.js
+
+Caused by:
+[WILDCARD]