fix #416

Author: xuhuanzy

crates/emmylua_code_analysis/src/compilation/test/closure_param_infer_test.rs

@@ -274,4 +274,49 @@ mod test {
         let expected = ws.ty("number");
         assert_eq!(ws.humanize_type(ty), ws.humanize_type(expected));
     }
+
+    #[test]
+    fn test_issue_416() {
+        let mut ws = VirtualWorkspace::new();
+        ws.def_files(vec![
+            (
+                "test.lua",
+                r#"
+                ---@class CustomEvent
+                ---@field private custom_event_manager? EventManager
+                local M = {}
+
+                ---@return EventManager
+                function newEventManager()
+                end
+
+                function M:event_on()
+                    if not self.custom_event_manager then
+                        self.custom_event_manager = newEventManager()
+                    end
+                    local trigger = self.custom_event_manager:get_trigger()
+                    A = trigger
+                    return trigger
+                end
+            "#,
+            ),
+            (
+                "test2.lua",
+                r#"
+                ---@class Trigger
+
+                ---@class EventManager
+                local EventManager
+
+                ---@return Trigger
+                function EventManager:get_trigger()
+                end
+            "#,
+            ),
+        ]);
+
+        let ty = ws.expr_ty("A");
+        let expected = ws.ty("Trigger");
+        assert_eq!(ws.humanize_type(ty), ws.humanize_type(expected));
+    }
 }

crates/emmylua_code_analysis/src/db_index/type/type_assert.rs

@@ -95,7 +95,9 @@ impl TypeAssertion {
             TypeAssertion::Or(a) => {
                 let mut result = vec![];
                 for assertion in a.iter() {
-                    result.push(assertion.tighten_type(db, config, root, source.clone())?);
+                    if let Ok(t) = assertion.tighten_type(db, config, root, source.clone()) {
+                        result.push(t);
+                    }
                 }
 
                 match result.len() {