fix: fix extra warnings

lib/fs.c

@@ -21,7 +21,7 @@ fs_read_to_str (const char *path)
 
     if (path && (fp = fopen (path, "r"))) {
         fseek (fp, 0, SEEK_END);
-        len = ftell (fp);
+        len = (usize) ftell (fp);
         fseek (fp, 0, SEEK_SET);
 
         buf = smalloc (len + 1);

lib/vec.c

@@ -68,7 +68,7 @@
     {                                                                         \
         usize i;                                                              \
         for (i = 0; i < n; i++)                                               \
-            a[i] = a[i] * b[i] + c[i];                                        \
+            a[i] = (TYPE) (a[i] * b[i]) + c[i];                               \
     }
 
 IMPLEMENT_FUNCTIONS(IMPL_VEC_ADD)

makefile

@@ -1,5 +1,5 @@
 CC := gcc
-CFLAGS := -Wall -Wextra -Werror=implicit -pedantic -Og -g -Ilib/inc
+CFLAGS := -Wall -Wextra -Werror=implicit -Wconversion -Wdouble-promotion -pedantic -g3 -fsanitize=address -fsanitize=undefined -Ilib/inc
 CLIBS := -lm
 
 SRCFILES := $(wildcard lib/*.c)