fix(compiler): Raise appropriate error on unbound export (#1528)

Author: ospencer

compiler/src/typed/typemod.re

@@ -601,7 +601,8 @@ let type_module = (~toplevel=false, funct_body, anchor, env, sstr /*scope*/) =>
             | None => Ident.create(name.txt)
             };
           let name = Identifier.IdentName(name);
-          let (p, {val_fullpath} as desc) = Env.lookup_value(name, env);
+          let (p, {val_fullpath} as desc) =
+            Typetexp.find_value(env, loc, name);
           (
             TSigValue(id, desc),
             {tex_id: id, tex_path: val_fullpath, tex_loc: loc},

compiler/test/suites/exports.re

@@ -87,6 +87,11 @@ describe("exports", ({test, testSkip}) => {
       ExposedType.apply((arg) => print("ok"))
     |},
   );
+  assertCompileError(
+    "regression_issue_1489",
+    "export foo",
+    "Unbound value foo",
+  );
 
   assertSnapshot("let_rec_export", "export let rec foo = () => 5");