Update esbuild.config

esbuild.config.mjs

@@ -12,8 +12,8 @@ if you want to view the source, please visit the github repository of this plugi
 
 const prod = process.argv[2] === "production";
 
-esbuild
-  .build({
+const context = await esbuild
+  .context({
     banner: {
       js: banner,
     },
@@ -43,11 +43,16 @@ esbuild
         preprocess: sveltePreprocess(),
       }),
     ],
-    watch: !prod,
     target: "es2018",
     logLevel: "info",
     sourcemap: prod ? false : "inline",
     treeShaking: true,
     outfile: "main.js",
   })
-  .catch(() => process.exit(1));
+
+if (prod) {
+  await context.rebuild();
+  process.exit(0);
+} else {
+  await context.watch();
+}