1 files changed, 25 insertions, 18 deletions
diff --git a/cli/tsc/99_main_compiler.js b/cli/tsc/99_main_compiler.js
index ddbb8fcac..d65aaa4c1 100644
--- a/cli/tsc/99_main_compiler.js
+++ b/cli/tsc/99_main_compiler.js
@@ -31,10 +31,22 @@ delete Object.prototype.__proto__;
       const stringifiedArgs = args.map((arg) =>
         typeof arg === "string" ? arg : JSON.stringify(arg)
       ).join(" ");
-      core.print(`DEBUG ${logSource} - ${stringifiedArgs}\n`);
+      // adding a non-zero integer value to the end of the debug string causes
+      // the message to be printed to stderr instead of stdout, which is better
+      // aligned to the behaviour of debug messages
+      core.print(`DEBUG ${logSource} - ${stringifiedArgs}\n`, 1);
     }
   }
 
+  function error(...args) {
+    const stringifiedArgs = args.map((arg) =>
+      typeof arg === "string" || arg instanceof Error
+        ? String(arg)
+        : JSON.stringify(arg)
+    ).join(" ");
+    core.print(`ERROR ${logSource} = ${stringifiedArgs}\n`, 1);
+  }
+
   class AssertionError extends Error {
     constructor(msg) {
       super(msg);
@@ -497,23 +509,18 @@ delete Object.prototype.__proto__;
         );
         return respond(id, sourceFile && sourceFile.text);
       }
-      case "getSemanticDiagnostics": {
-        const diagnostics = languageService.getSemanticDiagnostics(
-          request.specifier,
-        ).filter(({ code }) => !IGNORED_DIAGNOSTICS.includes(code));
-        return respond(id, fromTypeScriptDiagnostic(diagnostics));
-      }
-      case "getSuggestionDiagnostics": {
-        const diagnostics = languageService.getSuggestionDiagnostics(
-          request.specifier,
-        ).filter(({ code }) => !IGNORED_DIAGNOSTICS.includes(code));
-        return respond(id, fromTypeScriptDiagnostic(diagnostics));
-      }
-      case "getSyntacticDiagnostics": {
-        const diagnostics = languageService.getSyntacticDiagnostics(
-          request.specifier,
-        ).filter(({ code }) => !IGNORED_DIAGNOSTICS.includes(code));
-        return respond(id, fromTypeScriptDiagnostic(diagnostics));
+      case "getDiagnostics": {
+        try {
+          const diagnostics = [
+            ...languageService.getSemanticDiagnostics(request.specifier),
+            ...languageService.getSuggestionDiagnostics(request.specifier),
+            ...languageService.getSyntacticDiagnostics(request.specifier),
+          ].filter(({ code }) => !IGNORED_DIAGNOSTICS.includes(code));
+          return respond(id, fromTypeScriptDiagnostic(diagnostics));
+        } catch (e) {
+          error(e);
+          return respond(id, []);
+        }
       }
       case "getQuickInfo": {
         return respond(