Fix merge into a custom resolver node that raises an exception

news/486.bugfix

@@ -0,0 +1 @@
+Fix merge into a custom resolver node that raises an exception

omegaconf/base.py

@@ -402,8 +402,11 @@ def _resolve_simple_interpolation(
                         ),
                     )
                 except Exception as e:
-                    self._format_and_raise(key=inter_key, value=None, cause=e)
-                    assert False
+                    if throw_on_resolution_failure:
+                        self._format_and_raise(key=inter_key, value=None, cause=e)
+                        assert False
+                    else:
+                        return None
             else:
                 if throw_on_resolution_failure:
                     raise UnsupportedInterpolationType(

tests/test_merge.py

@@ -581,3 +581,17 @@ def test_merge_with_error_not_changing_target(c1: Any, c2: Any) -> Any:
     with pytest.raises(ValidationError):
         c1.merge_with(c2)
     assert c1 == backup
+
+
+def test_into_custom_resolver_that_throws(restore_resolvers: Any) -> None:
+    def fail() -> None:
+        raise ValueError()
+
+    OmegaConf.register_resolver("fail", fail)
+
+    configs = (
+        {"d": 20, "i": "${fail:}"},
+        {"i": "zzz"},
+    )
+    expected = {"d": 20, "i": "zzz"}
+    assert OmegaConf.merge(*configs) == expected