Better NotFound error handling in CodeFetch

throwResolutionError was swallowing unrelated errors.

js/compiler.ts

@@ -117,20 +117,6 @@ export class ModuleMetaData implements ts.IScriptSnapshot {
   }
 }
 
-/**
- * Throw a module resolution error, when a module is unsuccessfully resolved.
- */
-function throwResolutionError(
-  message: string,
-  moduleSpecifier: ModuleSpecifier,
-  containingFile: ContainingFile
-): never {
-  throw new Error(
-    // tslint:disable-next-line:max-line-length
-    `Cannot resolve module "${moduleSpecifier}" from "${containingFile}".\n  ${message}`
-  );
-}
-
 /**
  * A singleton class that combines the TypeScript Language Service host API
  * with Deno specific APIs to provide an interface for compiling and running
@@ -514,9 +500,9 @@ export class DenoCompiler
     if (fileName && this._moduleMetaDataMap.has(fileName)) {
       return this._moduleMetaDataMap.get(fileName)!;
     }
-    let moduleId: ModuleId = "";
+    let moduleId: ModuleId;
-    let sourceCode: SourceCode | undefined;
+    let sourceCode: SourceCode;
-    let outputCode: OutputCode | undefined;
+    let outputCode: OutputCode | null;
     if (
       moduleSpecifier.startsWith(ASSETS) ||
       containingFile.startsWith(ASSETS)
@@ -524,38 +510,24 @@ export class DenoCompiler
       // Assets are compiled into the runtime javascript bundle.
       // we _know_ `.pop()` will return a string, but TypeScript doesn't so
       // not null assertion
-      const moduleId = moduleSpecifier.split("/").pop()!;
+      moduleId = moduleSpecifier.split("/").pop()!;
       const assetName = moduleId.includes(".") ? moduleId : `${moduleId}.d.ts`;
       assert(assetName in assetSourceCode, `No such asset "${assetName}"`);
       sourceCode = assetSourceCode[assetName];
       fileName = `${ASSETS}/${assetName}`;
+      outputCode = "";
     } else {
       // We query Rust with a CodeFetch message. It will load the sourceCode,
       // and if there is any outputCode cached, will return that as well.
-      let fetchResponse;
+      const fetchResponse = this._os.codeFetch(moduleSpecifier, containingFile);
-      try {
+      moduleId = fetchResponse.moduleName!;
-        fetchResponse = this._os.codeFetch(moduleSpecifier, containingFile);
+      fileName = fetchResponse.filename!;
-      } catch (e) {
+      sourceCode = fetchResponse.sourceCode!;
-        return throwResolutionError(
+      outputCode = fetchResponse.outputCode!;
-          `os.codeFetch message: ${e.message}`,
-          moduleSpecifier,
-          containingFile
-        );
-      }
-      moduleId = fetchResponse.moduleName || "";
-      fileName = fetchResponse.filename || undefined;
-      sourceCode = fetchResponse.sourceCode || undefined;
-      outputCode = fetchResponse.outputCode || undefined;
-    }
-    if (!sourceCode || sourceCode.length === 0 || !fileName) {
-      return throwResolutionError(
-        "Invalid source code or file name.",
-        moduleSpecifier,
-        containingFile
-      );
     }
+    assert(sourceCode!.length > 0);
     this._log("resolveModule sourceCode length:", sourceCode.length);
-    this._log("resolveModule has outputCode:", !!outputCode);
+    this._log("resolveModule has outputCode:", outputCode! != null);
     this._setFileName(moduleSpecifier, containingFile, fileName);
     if (fileName && this._moduleMetaDataMap.has(fileName)) {
       return this._moduleMetaDataMap.get(fileName)!;

src/deno_dir.rs

@@ -1,6 +1,7 @@
 // Copyright 2018 the Deno authors. All rights reserved. MIT license.
 use errors::DenoError;
 use errors::DenoResult;
+use errors::ErrorKind;
 use fs as deno_fs;
 use net;
 use ring;
@@ -159,7 +160,7 @@ impl DenoDir {
     let (module_name, filename) =
       self.resolve_module(module_specifier, containing_file)?;
 
-    let out = self
+    let result = self
       .get_source_code(module_name.as_str(), filename.as_str())
       .and_then(|source_code| {
         Ok(CodeFetchOutput {
@@ -168,7 +169,24 @@ impl DenoDir {
           source_code,
           maybe_output_code: None,
         })
-      })?;
+      });
+    let out = match result {
+      Err(err) => {
+        if err.kind() == ErrorKind::NotFound {
+          // For NotFound, change the message to something better.
+          return Err(DenoError::from(std::io::Error::new(
+            std::io::ErrorKind::NotFound,
+            format!(
+              "Cannot resolve module \"{}\" from \"{}\"",
+              module_specifier, containing_file
+            ),
+          )));
+        } else {
+          return Err(err);
+        }
+      }
+      Ok(out) => out,
+    };
 
     let result =
       self.load_cache(out.filename.as_str(), out.source_code.as_str());

tests/error_004_missing_module.ts.out

@@ -1,12 +1,11 @@
-Error: Cannot resolve module "bad-module.ts" from "[WILDCARD]error_004_missing_module.ts".
+NotFound: Cannot resolve module "bad-module.ts" from "[WILDCARD]/tests/error_004_missing_module.ts"
-  os.codeFetch message: [WILDCARD] (os error 2)
+    at maybeError (deno/js/errors.ts:[WILDCARD])
-    at throwResolutionError (deno/js/compiler.ts:[WILDCARD])
+    at maybeThrowError (deno/js/errors.ts:[WILDCARD])
+    at send (deno/js/fbs_util.ts:[WILDCARD])
+    at Object.codeFetch (deno/js/os.ts:[WILDCARD])
     at DenoCompiler.resolveModule (deno/js/compiler.ts:[WILDCARD])
     at DenoCompiler._resolveModuleName (deno/js/compiler.ts:[WILDCARD])
     at moduleNames.map.name (deno/js/compiler.ts:[WILDCARD])
     at Array.map (<anonymous>)
     at DenoCompiler.resolveModuleNames (deno/js/compiler.ts:[WILDCARD])
     at Object.compilerHost.resolveModuleNames (deno/third_party/node_modules/typescript/lib/typescript.js:[WILDCARD])
-    at resolveModuleNamesWorker (deno/third_party/node_modules/typescript/lib/typescript.js:[WILDCARD])
-    at resolveModuleNamesReusingOldState (deno/third_party/node_modules/typescript/lib/typescript.js:[WILDCARD])
-    at processImportedModules (deno/third_party/node_modules/typescript/lib/typescript.js:[WILDCARD])

tests/error_005_missing_dynamic_import.ts.out

@@ -1,12 +1,11 @@
-Error: Cannot resolve module "bad-module.ts" from "[WILDCARD]deno/tests/error_005_missing_dynamic_import.ts".
+NotFound: Cannot resolve module "bad-module.ts" from "[WILDCARD]deno/tests/error_005_missing_dynamic_import.ts"
-  os.codeFetch message: [WILDCARD] (os error 2)
+    at maybeError (deno/js/errors.ts:[WILDCARD])
-    at throwResolutionError (deno/js/compiler.ts:[WILDCARD])
+    at maybeThrowError (deno/js/errors.ts:[WILDCARD])
+    at send (deno/js/fbs_util.ts:[WILDCARD])
+    at Object.codeFetch (deno/js/os.ts:[WILDCARD])
     at DenoCompiler.resolveModule (deno/js/compiler.ts:[WILDCARD])
     at DenoCompiler._resolveModuleName (deno/js/compiler.ts:[WILDCARD])
     at moduleNames.map.name (deno/js/compiler.ts:[WILDCARD])
     at Array.map (<anonymous>)
     at DenoCompiler.resolveModuleNames (deno/js/compiler.ts:[WILDCARD])
     at Object.compilerHost.resolveModuleNames (deno/third_party/node_modules/typescript/lib/typescript.js:[WILDCARD])
-    at resolveModuleNamesWorker (deno/third_party/node_modules/typescript/lib/typescript.js:[WILDCARD])
-    at resolveModuleNamesReusingOldState (deno/third_party/node_modules/typescript/lib/typescript.js:[WILDCARD])
-    at processImportedModules (deno/third_party/node_modules/typescript/lib/typescript.js:[WILDCARD])