message: sst start: print descriptive error for handler not found error
diff: @@ -690,15 +690,18 @@ function handleRunTypeCheck(srcPath, inputFiles, tsconfig, config) {
  async function getHandlerFilePath(appPath, srcPath, handler) {
  // Check entry path exists
  - let entryPath = "";
  + let entryPath;
  const entryPathExists = [".ts", ".tsx", ".js", ".jsx"].some((ext) => {
  entryPath = path.join(appPath, srcPath, addExtensionToHandler(handler, ext));
  return fs.existsSync(entryPath);
  });
  + // Print out the error message and throw
  if (!entryPathExists) {
  const handlerPosixPath = getHandlerFullPosixPath(srcPath, handler);
  - throw new Error(`Cannot find a handler file for "${handlerPosixPath}".`);
  + const errorMessage = `Cannot find a handler file for "${handlerPosixPath}"`;
  + logger.error(`${chalk.red("error")} ${errorMessage}\n`);
  + throw new Error(errorMessage);
  }
  return entryPath;
  