Fix issue in Js.Promise2 where then and catch were returning undefined

master version of PR #5996

Author: cristianoc

CHANGELOG.md

@@ -61,6 +61,7 @@ These are only breaking changes for unformatted code.
 - Fix issue with overlapping labelled argument with default value https://github.com/rescript-lang/rescript-compiler/pull/5989
 - Fix issue with using alias and default value together https://github.com/rescript-lang/rescript-compiler/pull/5989
 - GenType: fix issue with V3 compatibility mode (see https://github.com/rescript-lang/rescript-compiler/issues/5990) https://github.com/rescript-lang/rescript-compiler/pull/5991
+- Fix issue in `Js.Promise2` where `then` and `catch` were returning `undefined` https://github.com/rescript-lang/rescript-compiler/pull/5997
 
 #### :nail_care: Polish
 

jscomp/others/js_promise2.res

@@ -4,14 +4,14 @@ type error
 /** Type-safe t-first then */
 let then: (promise<'a>, 'a => promise<'b>) => promise<'b> = %raw(`
   function(p, cont) {
-    Promise.resolve(p).then(cont)
+    return Promise.resolve(p).then(cont)
   }
   `)
 
 /** Type-safe t-first catch */
 let catch: (promise<'a>, error => promise<'a>) => promise<'a> = %raw(`
     function(p, cont) {
-      Promise.resolve(p).catch(cont)
+      return Promise.resolve(p).catch(cont)
     }
     `)
 

lib/es6/js_promise2.js

@@ -2,11 +2,11 @@
 
 
 var then = (function(p, cont) {
-    Promise.resolve(p).then(cont)
+    return Promise.resolve(p).then(cont)
   });
 
 var $$catch = (function(p, cont) {
-      Promise.resolve(p).catch(cont)
+      return Promise.resolve(p).catch(cont)
     });
 
 export {

lib/js/js_promise2.js

@@ -2,11 +2,11 @@
 
 
 var then = (function(p, cont) {
-    Promise.resolve(p).then(cont)
+    return Promise.resolve(p).then(cont)
   });
 
 var $$catch = (function(p, cont) {
-      Promise.resolve(p).catch(cont)
+      return Promise.resolve(p).catch(cont)
     });
 
 exports.then = then;