Build fails if -Wpedantic-errors or -Weverything compiler flags are set

[kernelwernel]

as the title says, the build process fails if either flags are included in my CMAKE_CXX_FLAGS. I've provided a replication of the error:

error:

CMake Error at cmake/modules.cmake:135 (add_library):
  No SOURCES given to target: MODULES
Call Stack (most recent call first):
  CMakeLists.txt:27 (add_module_library)

file structure:

.
├── cmake
│   └── modules.cmake
├── CMakeLists.txt
└── src
    ├── hello.cpp
    ├── main.cpp
    └── subdir
        └── bye.cpp

CMakeLists.txt:

cmake_minimum_required(VERSION 3.26)
project(modtest)

set(CMAKE_CXX_STANDARD 20)
set(CMAKE_CXX_STANDARD_REQUIRED ON)

# this works
#set(CMAKE_CXX_FLAGS "-w -Wall -Wextra -Werror -Wshadow -Wconversion -Wunused -Wpedantic")
# but this doesn't
set(CMAKE_CXX_FLAGS "-w -Wall -Wextra -Werror -Wshadow -Wconversion -Wunused -Wpedantic -Wpedantic-errors -Weverything")

set(PROJECT "${CMAKE_CURRENT_SOURCE_DIR}")
set(TARGET "modtest")

file(GLOB_RECURSE SRC "${PROJECT}/src/*.cpp")

add_executable(${TARGET} ${PROJECT}/src/main.cpp)

include(cmake/modules.cmake)

add_module_library(MODULES ${SRC})

target_link_libraries(${TARGET} PRIVATE MODULES)

main:

import hello;
import bye;

int main() {
    hello();
    bye();
}

hello:

module;

#include <iostream>

export module hello;

export void hello() {
    std::cout << "hello\n";
}

bye:

module;

#include <iostream>

export module bye;

export void bye() {
    std::cout << "bye\n";
}