Declare docgen globals before generating docs

Author: dlarocque

scripts/docgen/docgen.ts

@@ -58,6 +58,9 @@ const PREFERRED_PARAMS = [
   'vertexAI'
 ];
 
+let authApiReportOriginal: string;
+let authApiConfigOriginal: string;
+
 yargs
   .command(
     '$0',
@@ -93,9 +96,6 @@ yargs
 process.on('exit', cleanup);
 process.on('SIGINT', cleanup);
 
-let authApiReportOriginal: string;
-let authApiConfigOriginal: string;
-
 function cleanup() {
   try {
     // Restore original auth api-extractor.json contents.