fix(typescript): erase default export if exporting a TS type (#10019)

packages/babel-plugin-transform-typescript/src/index.js

@@ -156,6 +156,16 @@ export default declare((api, { jsxPragma = "React" }) => {
         }
       },
 
+      ExportDefaultDeclaration(path, { exportableTSNames }) {
+        // remove whole declaration if it's exporting a TS type
+        if (
+          t.isIdentifier(path.node.declaration) &&
+          exportableTSNames.has(path.node.declaration.name)
+        ) {
+          path.remove();
+        }
+      },
+
       TSDeclareFunction(path) {
         path.remove();
       },

packages/babel-plugin-transform-typescript/test/fixtures/declarations/erased/input.mjs

@@ -42,6 +42,7 @@ function foo() {}
 export { II3 as default, AA2 as A, BB2 as BB3, foo }; // only BB2 and foo
 
 // export an interface before declaration
+export default Bar;
 export { Bar } // everything removed
 export { Bar as Bar2, C2 as C4 } // only C4
 interface Bar {}