add new error files

add the error files from sdl_template.
they are called 'error' instead of 'errors'.
'error' shall replace 'errors' in a following commit

src/error.c

@@ -0,0 +1,71 @@
+#include "error.h"
+
+#include <SDL_messagebox.h>
+#include <stdarg.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdnoreturn.h>
+
+#define PRINT_BUFFER_SIZE 128 // defines the buffer size for printing
+
+// writes the arguments to the specified buffer
+// using a macro instead of an inline function because fmt otherwise gets horribly messed up
+#define write_args(buf, fmt)                            \
+    va_list args;                                       \
+    va_start(args, fmt);                                \
+    (void)vsnprintf(buf, PRINT_BUFFER_SIZE, fmt, args); \
+    va_end(args);
+
+static gamestatus status = STATUS_RUNNING;
+
+void set_gamestatus(gamestatus nstatus) {
+    status = nstatus;
+}
+
+gamestatus get_gamestatus(void) {
+    return status;
+}
+
+void debug(char const* fmt, ...) {
+    char const* env = getenv("DEBUG");
+    if (env == NULL || *env != '1')
+        return;
+
+    char buf[PRINT_BUFFER_SIZE] = {0};
+    write_args(buf, fmt);
+
+    (void)fprintf(stdout, "\033[95m%s\033[0m\n", buf);
+}
+
+void info(char const* fmt, ...) {
+    char buf[PRINT_BUFFER_SIZE] = {0};
+    write_args(buf, fmt);
+    (void)fprintf(stdout, "\033[0m%s\033[0m\n", buf); // write colour here for consistency
+}
+
+void warn(char const* fmt, ...) {
+    char buf[PRINT_BUFFER_SIZE] = {0};
+    write_args(buf, fmt);
+    (void)fprintf(stderr, "\033[93mW: %s\033[0m\n", buf);
+}
+
+void error(char const* fmt, ...) {
+    char buf[PRINT_BUFFER_SIZE] = {0};
+    write_args(buf, fmt);
+    (void)fprintf(stderr, "\033[mW: %s\033[0m", buf);
+}
+
+noreturn void fatal(gamestatus error_code, char const* fname, uint32_t ln, char const* fmt, ...) {
+    char buf1[PRINT_BUFFER_SIZE] = {0};
+    write_args(buf1, fmt);
+
+    char buf2[PRINT_BUFFER_SIZE * 2] = {0};
+    sprintf(buf2, "%s\n    at %s:%u (exitcode: %u)", buf1, fname, ln, error_code);
+
+    (void)fprintf(stderr, "\033[91mE: %s\033[0m\n", buf2);
+    SDL_ShowSimpleMessageBox(SDL_MESSAGEBOX_ERROR, "something went wrong! :O", buf2, NULL);
+
+    // set status, but exit immediately, as code is not allowed to execute beyond this point
+    set_gamestatus(error_code);
+    exit(status);
+}