message: Fix interpolated string `Failed to generate docs...`
  A string was using the wrong kind of quotes and so the interpolated fields weren't.
diff: @@ -150,7 +150,7 @@ export class TechdocsGenerator implements GeneratorBase {
  `Failed to generate docs from ${inputDir} into ${outputDir}`,
  );
  throw new ForwardedError(
  - 'Failed to generate docs from ${inputDir} into ${outputDir}',
  + `Failed to generate docs from ${inputDir} into ${outputDir}`,
  error,
  );
  }
  