fix(webpack): Await source map deletion before signaling build completion (#918)

* fix(webpack): Await source map deletion before signaling build completion

This PR reworks the webpack plugin to await the source map deletion before
moving on. This matches the behavior of the rollup and esbuild plugins.

* Clean up code structure to use try/catch/await

Author: andreiborza

packages/webpack-plugin/src/webpack4and5.ts

@@ -277,28 +277,30 @@ export function sentryWebpackPluginFactory({
 
         compiler.hooks.afterEmit.tapAsync(
           "sentry-webpack-plugin",
-          (compilation: WebpackCompilation, callback: () => void) => {
+          (compilation: WebpackCompilation, callback: (err?: Error) => void) => {
             const freeGlobalDependencyOnBuildArtifacts = createDependencyOnBuildArtifacts();
             const upload = createDebugIdUploadFunction({ sentryBuildPluginManager });
 
-            void sentryBuildPluginManager
-              .createRelease()
-              .then(async () => {
+            const run = async (): Promise<void> => {
+              try {
+                await sentryBuildPluginManager.createRelease();
                 if (sourcemapsEnabled && options.sourcemaps?.disable !== "disable-upload") {
                   const outputPath = compilation.outputOptions.path ?? path.resolve();
                   const buildArtifacts = Object.keys(compilation.assets).map((asset) =>
                     path.join(outputPath, asset)
                   );
                   await upload(buildArtifacts);
                 }
-              })
-              .then(() => {
-                callback();
-              })
-              .finally(() => {
+              } finally {
                 freeGlobalDependencyOnBuildArtifacts();
-                void sentryBuildPluginManager.deleteArtifacts();
-              });
+                await sentryBuildPluginManager.deleteArtifacts();
+              }
+            };
+
+            run().then(
+              () => callback(),
+              (err: Error) => callback(err)
+            );
           }
         );