fix #317

Author: xuhuanzy

crates/emmylua_code_analysis/src/diagnostic/test/undefined_field_test.rs

@@ -194,4 +194,22 @@ mod test {
             "#
         ));
     }
+
+    #[test]
+    fn test_issue_317() {
+        let mut ws = VirtualWorkspace::new();
+        assert!(ws.check_code_for(
+            DiagnosticCode::UndefinedField,
+            r#"
+                --- @class A
+                --- @field [string] string
+                --- @field [integer] integer
+                local foo = {}
+
+                local bar = foo[1]
+
+
+            "#
+        ));
+    }
 }

crates/emmylua_code_analysis/src/semantic/infer/infer_index.rs

@@ -511,8 +511,10 @@ fn infer_member_by_index_custom_type(
                 .ok_or(InferFailReason::None)?;
             let operand = operator.get_operand(db);
             let return_type = operator.get_result(db)?;
-            let typ = infer_index_metamethod(db, cache, &index_key, &operand, &return_type)?;
-            return Ok(typ);
+            let typ = infer_index_metamethod(db, cache, &index_key, &operand, &return_type);
+            if let Ok(typ) = typ {
+                return Ok(typ);
+            }
         }
     }