fix: providing empty source code for missing compiled files (#6760)

This commit adds a fallback mechanism for absent compiled source file.

Because imported type declaration files are not emitted by TS compiler
and their imports are not elided users often hit "No such file or directory"
error. With this commit in such situation an empty source file will be
provided to V8 with a warning to the user suggesting using "import type"/
"export type" syntax instead.

cli/global_state.rs

@@ -9,7 +9,6 @@ use crate::module_graph::ModuleGraphFile;
 use crate::module_graph::ModuleGraphLoader;
 use crate::msg;
 use crate::msg::MediaType;
-use crate::op_error::OpError;
 use crate::permissions::Permissions;
 use crate::state::exit_unstable;
 use crate::tsc::CompiledModule;
@@ -236,16 +235,22 @@ impl GlobalState {
     };
 
     let compiled_module = if was_compiled {
-      state1
-        .ts_compiler
-        .get_compiled_module(&out.url)
-        .map_err(|e| {
-          let msg = e.to_string();
-          OpError::other(format!(
-            "Failed to get compiled source code of {}.\nReason: {}",
-            out.url, msg
-          ))
-        })?
+      match state1.ts_compiler.get_compiled_module(&out.url) {
+        Ok(module) => module,
+        Err(e) => {
+          let msg = format!(
+            "Failed to get compiled source code of \"{}\".\nReason: {}\n\
+            If the source file provides only type exports, prefer to use \"import type\" or \"export type\" syntax instead.",
+            out.url, e.to_string()
+          );
+          info!("{} {}", crate::colors::yellow("Warning"), msg);
+
+          CompiledModule {
+            code: "".to_string(),
+            name: out.url.to_string(),
+          }
+        }
+      }
     } else {
       CompiledModule {
         code: String::from_utf8(out.source_code.clone())?,

cli/tests/integration_tests.rs

@@ -1972,6 +1972,11 @@ itest!(ts_decorators {
   output: "ts_decorators.ts.out",
 });
 
+itest!(ts_type_only_import {
+  args: "run --reload ts_type_only_import.ts",
+  output: "ts_type_only_import.ts.out",
+});
+
 itest!(swc_syntax_error {
   args: "run --reload swc_syntax_error.ts",
   output: "swc_syntax_error.ts.out",

cli/tests/ts_type_only_import.d.ts

@@ -0,0 +1,3 @@
+export interface HelloWorld {
+  a: string;
+}

cli/tests/ts_type_only_import.ts

@@ -0,0 +1 @@
+export * from "./ts_type_only_import.d.ts";

cli/tests/ts_type_only_import.ts.out

@@ -0,0 +1,4 @@
+Check [WILDCARD]ts_type_only_import.ts
+Warning Failed to get compiled source code of "[WILDCARD]ts_type_only_import.d.ts".
+Reason: [WILDCARD] (os error 2)
+If the source file provides only type exports, prefer to use "import type" or "export type" syntax instead.