feat(error/expect): use panic instead of raising Failure

src/Core__Option.mjs

@@ -2,6 +2,7 @@
 
 import * as Curry from "rescript/lib/es6/curry.js";
 import * as Caml_option from "rescript/lib/es6/caml_option.js";
+import * as Core__Error from "./Core__Error.mjs";
 
 function flat(opt) {
   if (opt !== undefined) {
@@ -39,12 +40,9 @@ function getExn(opt) {
 function expect(opt, message) {
   if (opt !== undefined) {
     return Caml_option.valFromOption(opt);
+  } else {
+    return Core__Error.panic(message);
   }
-  throw {
-        RE_EXN_ID: "Failure",
-        _1: message,
-        Error: new Error()
-      };
 }
 
 function mapWithDefault(opt, $$default, f) {

src/Core__Option.res

@@ -53,7 +53,7 @@ let getExn = opt =>
 let expect = (opt, message) =>
   switch opt {
   | Some(value) => value
-  | None => raise(Failure(message))
+  | None => Core__Error.panic(message)
   }
 
 external getUnsafe: option<'a> => 'a = "%identity"

src/Core__Option.resi

@@ -101,7 +101,7 @@ Option.expect(None, "should not be None") // Raises `Failure("should not be None
 
 ## Exceptions
 
-- Raises `Failure` if `opt` is `None`
+- Panics if `opt` is `None`
 */
 let expect: (option<'a>, string) => 'a