error: add proper error strings

Co-authored-by: tema5002 <tema5002@tuta.io>
Reviewed-on: NeoFlock/noom#3
Co-committed-by: tema5002 <tema5002@tuta.io>

src/helper.h

@@ -2,6 +2,8 @@
 
 int noom_startswith(const char* str, const char* compare);
 int noom_streql(const char* stra, noom_uint_t lena, const char* strb, noom_uint_t lenb); // rename to something better?
+noom_uint_t noom_strlen(const char *s);
+void noom_safe_strcpy(char* buffer, noom_uint_t* pos, noom_uint_t buffer_size, const char* src);
 
 void* noom_alloc(noom_uint_t size);
 void noom_free(void* ptr);