Enable the -Wextra compiler flag in the wren.mk build configuration, which was previously commented out with a TODO. To handle the new unused parameter warnings triggered by -Wextra (particularly for WrenVM* vm parameters in several functions), add -Wno-unused-parameter to suppress them. Also fix a declaration ordering issue in wren_vm.c where the 'static' keyword was placed after the return type in loadIntoCore, moving it to the correct position before the type specifier.
The guard checks if the VM pointer is NULL or if its methodNames count is zero,
which serves as a heuristic to detect an already-freed VM instance. This prevents
a segmentation fault or memory corruption when wrenFreeVM is called multiple times
on the same VM object.
