Build: Add a plugin to throw unexpected warnings (#12463)

scripts/build/bundler.mjs

@@ -12,6 +12,7 @@ import esbuildPluginReplaceText from "./esbuild-plugins/replace-text.mjs";
 import esbuildPluginLicense from "./esbuild-plugins/license.mjs";
 import esbuildPluginUmd from "./esbuild-plugins/umd.mjs";
 import esbuildPluginVisualizer from "./esbuild-plugins/visualizer.mjs";
+import esbuildPluginThrowWarnings from "./esbuild-plugins/throw-warnings.mjs";
 import bundles from "./config.mjs";
 
 const { __dirname, readJsonSync, require } = createEsmUtils(import.meta);
@@ -170,6 +171,7 @@ function* getEsbuildOptions(bundle, buildOptions) {
         }),
       buildOptions.reports &&
         esbuildPluginVisualizer({ formats: buildOptions.reports }),
+      esbuildPluginThrowWarnings(),
     ].filter(Boolean),
     minify: shouldMinify,
     legalComments: "none",
@@ -242,7 +244,9 @@ async function runBuild(bundle, esbuildOptions, buildOptions) {
   await esbuild.build({
     ...esbuildOptions,
     define: {},
-    plugins: plugins.filter(({ name }) => name === "umd"),
+    plugins: plugins.filter(
+      ({ name }) => name === "umd" || name === "throw-warnings"
+    ),
     entryPoints: [outfile],
     allowOverwrite: true,
   });

scripts/build/esbuild-plugins/throw-warnings.mjs

@@ -0,0 +1,22 @@
+const ignoredWarnings = new Set([
+  // Duplicated case clause
+  "This case clause will never be evaluated because it duplicates an earlier case clause",
+]);
+
+export default function esbuildPluginThrowWarnings() {
+  return {
+    name: "throw-warnings",
+    setup(build) {
+      build.onEnd(({ warnings }) => {
+        for (const warning of warnings) {
+          if (ignoredWarnings.has(warning.text)) {
+            continue;
+          }
+
+          console.log(warning);
+          throw new Error(warning.text);
+        }
+      });
+    },
+  };
+}