refactor: simplify sourcemap compilation scripts and add optional chaining for idempotency token access

Author: thiyaguk09

handwritten/storage/package.json

@@ -54,20 +54,21 @@
     "compile:cjs": "tsc -p ./tsconfig.cjs.json",
     "compile:esm": "tsc -p .",
     "compile": "npm run compile:cjs && npm run compile:esm",
+    "compile:sourcemaps": "npm run compile:cjs -- --sourceMap && npm run compile:esm -- --sourceMap",
     "conformance-test": "mocha --parallel build/cjs/conformance-test/ --require build/cjs/conformance-test/globalHooks.js",
     "docs": "jsdoc -c .jsdoc.json",
     "fix": "gts fix",
     "lint": "gts check",
     "postcompile": "cp ./src/package-json-helper.cjs ./build/cjs/src && cp ./src/package-json-helper.cjs ./build/esm/src",
     "postcompile:cjs": "babel --plugins gapic-tools/build/src/replaceImportMetaUrl,gapic-tools/build/src/toggleESMFlagVariable build/cjs/src/util.js -o build/cjs/src/util.js && cp internal-tooling/helpers/package.cjs.json build/cjs/package.json",
     "precompile": "rm -rf build/",
-    "preconformance-test": "npm run compile:cjs -- --sourceMap",
-    "predocs": "npm run compile:cjs -- --sourceMap",
+    "preconformance-test": "npm run compile:sourcemaps",
+    "predocs": "npm run compile:sourcemaps",
     "prelint": "cd samples; npm link ../; npm install",
     "prepare": "npm run compile",
     "presystem-test:esm": "npm run compile:esm",
-    "presystem-test": "npm run compile -- --sourceMap",
-    "pretest": "npm run compile -- --sourceMap",
+    "presystem-test": "npm run compile:sourcemaps",
+    "pretest": "npm run compile:sourcemaps",
     "samples-test": "npm link && cd samples/ && npm link ../ && npm test && cd ../",
     "system-test:esm": "mocha build/esm/system-test --timeout 600000 --exit",
     "system-test": "mocha build/cjs/system-test --timeout 600000 --exit",

handwritten/storage/src/resumable-upload.ts

@@ -810,11 +810,11 @@ export class Upload extends Writable {
       delete metadata.contentType;
     }
 
-    const userTokenKey = Object.keys(this.customRequestOptions.headers || {}).find(
+    const userTokenKey = Object.keys(this.customRequestOptions?.headers || {}).find(
       key => key.toLowerCase() === 'x-goog-gcs-idempotency-token'
     );
     if (userTokenKey) {
-      this.currentInvocationId.uri = this.customRequestOptions.headers![userTokenKey] as string;
+      this.currentInvocationId.uri = this.customRequestOptions?.headers?.[userTokenKey] as string;
     }
 
     let googAPIClient = `${getRuntimeTrackingString()} gccl/${
@@ -1010,11 +1010,11 @@ export class Upload extends Writable {
       },
     });
 
-    const userTokenKey = Object.keys(this.customRequestOptions.headers || {}).find(
+    const userTokenKey = Object.keys(this.customRequestOptions?.headers || {}).find(
       key => key.toLowerCase() === 'x-goog-gcs-idempotency-token'
     );
     if (userTokenKey) {
-      this.currentInvocationId.chunk = this.customRequestOptions.headers![userTokenKey] as string;
+      this.currentInvocationId.chunk = this.customRequestOptions?.headers?.[userTokenKey] as string;
     }
 
     let googAPIClient = `${getRuntimeTrackingString()} gccl/${
@@ -1235,11 +1235,11 @@ export class Upload extends Writable {
   async checkUploadStatus(
     config: CheckUploadStatusConfig = {},
   ): Promise<GaxiosResponse<FileMetadata | void>> {
-    const userTokenKey = Object.keys(this.customRequestOptions.headers || {}).find(
+    const userTokenKey = Object.keys(this.customRequestOptions?.headers || {}).find(
       key => key.toLowerCase() === 'x-goog-gcs-idempotency-token'
     );
     if (userTokenKey) {
-      this.currentInvocationId.checkUploadStatus = this.customRequestOptions.headers![userTokenKey] as string;
+      this.currentInvocationId.checkUploadStatus = this.customRequestOptions?.headers?.[userTokenKey] as string;
     }
 
     let googAPIClient = `${getRuntimeTrackingString()} gccl/${