Fix deleting non existent environments

that is an error caused by throwing a panic when an environment is not found and a nonexistent runner manager at the end of the chain is asked for it.

internal/environment/manager_handler_mock.go

@@ -1,4 +1,4 @@
-// Code generated by mockery v2.9.4. DO NOT EDIT.
+// Code generated by mockery v2.12.3. DO NOT EDIT.
 
 package environment
 
@@ -79,6 +79,20 @@ func (_m *ManagerHandlerMock) Get(id dto.EnvironmentID, fetch bool) (runner.Exec
 	return r0, r1
 }
 
+// HasNextHandler provides a mock function with given fields:
+func (_m *ManagerHandlerMock) HasNextHandler() bool {
+	ret := _m.Called()
+
+	var r0 bool
+	if rf, ok := ret.Get(0).(func() bool); ok {
+		r0 = rf()
+	} else {
+		r0 = ret.Get(0).(bool)
+	}
+
+	return r0
+}
+
 // List provides a mock function with given fields: fetch
 func (_m *ManagerHandlerMock) List(fetch bool) ([]runner.ExecutionEnvironment, error) {
 	ret := _m.Called(fetch)
@@ -118,9 +132,9 @@ func (_m *ManagerHandlerMock) NextHandler() ManagerHandler {
 	return r0
 }
 
-// SetNextHandler provides a mock function with given fields: m
-func (_m *ManagerHandlerMock) SetNextHandler(m ManagerHandler) {
-	_m.Called(m)
+// SetNextHandler provides a mock function with given fields: next
+func (_m *ManagerHandlerMock) SetNextHandler(next ManagerHandler) {
+	_m.Called(next)
 }
 
 // Statistics provides a mock function with given fields:
@@ -138,3 +152,18 @@ func (_m *ManagerHandlerMock) Statistics() map[dto.EnvironmentID]*dto.Statistica
 
 	return r0
 }
+
+type NewManagerHandlerMockT interface {
+	mock.TestingT
+	Cleanup(func())
+}
+
+// NewManagerHandlerMock creates a new instance of ManagerHandlerMock. It also registers a testing interface on the mock and a cleanup function to assert the mocks expectations.
+func NewManagerHandlerMock(t NewManagerHandlerMockT) *ManagerHandlerMock {
+	mock := &ManagerHandlerMock{}
+	mock.Mock.Test(t)
+
+	t.Cleanup(func() { mock.AssertExpectations(t) })
+
+	return mock
+}