Compiler exit before emit if preEmitDiagnostics found (#2441)

js/compiler.ts

@@ -379,15 +379,8 @@ window.compilerMain = function compilerMain(): void {
 
     const options = host.getCompilationSettings();
     const program = ts.createProgram(rootNames, options, host);
-    const emitResult = program!.emit();
 
-    // TODO(ry) Print diagnostics in Rust.
+    const preEmitDiagnostics = ts.getPreEmitDiagnostics(program).filter(
-    // https://github.com/denoland/deno/pull/2310
-
-    const diagnostics = ts
-      .getPreEmitDiagnostics(program)
-      .concat(emitResult.diagnostics)
-      .filter(
       ({ code }): boolean => {
         // TS2691: An import path cannot end with a '.ts' extension. Consider
         // importing 'bad-module' instead.
@@ -406,7 +399,19 @@ window.compilerMain = function compilerMain(): void {
         return true;
       }
     );
+    if (preEmitDiagnostics.length > 0) {
+      host._logDiagnostics(preEmitDiagnostics);
+      // The above _logDiagnostics calls os.exit(). The return is here just for
+      // clarity.
+      return;
+    }
 
+    const emitResult = program!.emit();
+
+    // TODO(ry) Print diagnostics in Rust.
+    // https://github.com/denoland/deno/pull/2310
+
+    const { diagnostics } = emitResult;
     if (diagnostics.length > 0) {
       host._logDiagnostics(diagnostics);
       // The above _logDiagnostics calls os.exit(). The return is here just for

tests/error_003_typescript2.test

@@ -0,0 +1,7 @@
+# Supposing that we've already attempted to run error_003_typescript.ts
+# we want to make sure that JS wasn't emitted. Running again without reload flag
+# should result in the same output.
+# https://github.com/denoland/deno/issues/2436
+args: run tests/error_003_typescript.ts
+exit_code: 1
+output: tests/error_003_typescript.ts.out