divide main.c into multiple modules

src/error.c

@@ -0,0 +1,18 @@
+#include "error.h"
+
+#include <stdarg.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdnoreturn.h>
+
+noreturn void fatal(char const* fmt, ...) {
+	char buf[128];
+	va_list args;
+	va_start(args, fmt);
+	vsnprintf(buf, 128, fmt, args);
+	va_end(args);
+
+	fprintf(stderr, "\033[91mE: %s\033[0m\n", buf);
+	exit(1);
+}