add error class

src/error.cpp

@@ -0,0 +1,20 @@
+#include "error.h"
+
+#include <assert.h>
+
+namespace cmkr::error {
+
+Status::Status(Code ec) noexcept : ec_(ec) {}
+
+Status::operator int() noexcept { return static_cast<int>(ec_); }
+
+} // namespace cmkr::error
+
+const char *err_string[] = {
+    "Success", "Runtime error", "Initialization error", "CMake generation error", "Build error",
+};
+
+const char *cmkr_error_status(int i) {
+    assert(i >= 0 && i < 5);
+    return err_string[i];
+}