build: workaround for jsii exit code issue (#2200)

Until aws/jsii#442 is released
we must fail builds on compilation errors. This is a temporary
workaround for this issue (if there is something in stdout
we consider that a compilation error).

tools/cdk-build-tools/lib/compile.ts

@@ -7,7 +7,13 @@ import { Timers } from "./timer";
  * Run the compiler on the current package
  */
 export async function compileCurrentPackage(timers: Timers, compilers: CompilerOverrides = {}): Promise<void> {
-  await shell(packageCompiler(compilers), timers);
+  const stdout = await shell(packageCompiler(compilers), timers);
+
+  // WORKAROUND: jsii 0.8.2 does not exit with non-zero on compilation errors
+  // until this is released: https://github.com/awslabs/jsii/pull/442
+  if (stdout.trim()) {
+    throw new Error(`Compilation failed`);
+  }
 
   // Find files in bin/ that look like they should be executable, and make them so.
   const scripts = currentPackageJson().bin || {};