Fix leftover assert false in code for null != undefined

Fixes #7225

Author: cristianoc

CHANGELOG.md

@@ -15,6 +15,7 @@
 #### :bug: Bug fix
 
 - Editor: Fix issue where pipe completions would not trigger with generic type arguments. https://github.com/rescript-lang/rescript/pull/7231
+- Fix leftover assert false in code for `null != undefined`. https://github.com/rescript-lang/rescript/pull/???
 
 # 12.0.0-alpha.7
 

compiler/core/js_exp_make.ml

@@ -1752,9 +1752,7 @@ let neq_null_undefined_boolean ?comment (a : t) (b : t) =
     true_
   | Null, Null | Undefined _, Undefined _ -> false_
   | Null, Undefined _ | Undefined _, Null -> true_
-  | _ ->
-    let _ = assert false in
-    {expression_desc = Bin (NotEqEq, a, b); comment}
+  | _ -> {expression_desc = Bin (NotEqEq, a, b); comment}
 
 let make_exception (s : string) =
   pure_runtime_call Primitive_modules.exceptions Literals.create [str s]

tests/tests/src/test_zero_nullable.mjs

@@ -295,12 +295,15 @@ eq("File \"test_zero_nullable.res\", line 255, characters 5-12", f1$1(undefined)
 
 Mt.from_pair_suites("Test_zero_nullable", suites.contents);
 
+let _null_undefined_neq;
+
 export {
   suites,
   test_id,
   eq,
   Test_null,
   Test_def,
   Test_null_def,
+  _null_undefined_neq,
 }
 /* u Not a pure module */

tests/tests/src/test_zero_nullable.res

@@ -256,3 +256,9 @@ let () = {
 }
 
 let () = Mt.from_pair_suites(__MODULE__, suites.contents)
+
+let _null_undefined_neq = {
+  let a = null
+  let b = undefined
+  let res = a != b
+}