Ignore AMP errors caused by React (for now)

Author: eps1lon

packages/next/src/export/routes/pages.ts

@@ -138,7 +138,40 @@ export async function exportPagesPage(
   ) => {
     const validator = await getAmpValidatorInstance(validatorPath)
     const result = validator.validateString(rawAmpHtml)
-    const errors = result.errors.filter((e) => e.severity === 'ERROR')
+    const errors = result.errors.filter((error) => {
+      if (error.severity === 'ERROR') {
+        // Unclear yet if these actually prevent the page from being indexed by the AMP cache.
+        // These are coming from React so all we can do is ignore them for now.
+
+        // <link rel="expect" blocking="render" />
+        // https://github.com/ampproject/amphtml/issues/40279
+        if (
+          error.code === 'DISALLOWED_ATTR' &&
+          error.params[0] === 'blocking' &&
+          error.params[1] === 'link'
+        ) {
+          return false
+        }
+        // <template> without type
+        if (
+          error.code === 'MANDATORY_ATTR_MISSING' &&
+          error.params[0] === 'type' &&
+          error.params[1] === 'template'
+        ) {
+          return false
+        }
+        // <template> without type
+        if (
+          error.code === 'MISSING_REQUIRED_EXTENSION' &&
+          error.params[0] === 'template' &&
+          error.params[1] === 'amp-mustache'
+        ) {
+          return false
+        }
+        return true
+      }
+      return false
+    })
     const warnings = result.errors.filter((e) => e.severity !== 'ERROR')
 
     if (warnings.length || errors.length) {