esp8266: Update lexer constructors so they can raise exceptions.

esp8266/lexerstr32.c

@@ -58,10 +58,7 @@ STATIC void str32_buf_free(void *sb_in) {
 }
 
 mp_lexer_t *mp_lexer_new_from_str32(qstr src_name, const char *str, mp_uint_t len, mp_uint_t free_len) {
-    mp_lexer_str32_buf_t *sb = m_new_obj_maybe(mp_lexer_str32_buf_t);
-    if (sb == NULL) {
-        return NULL;
-    }
+    mp_lexer_str32_buf_t *sb = m_new_obj(mp_lexer_str32_buf_t);
     sb->byte_off = (uint32_t)str & 3;
     sb->src_cur = (uint32_t*)(str - sb->byte_off);
     sb->val = *sb->src_cur++ >> sb->byte_off * 8;

esp8266/main.c

@@ -32,6 +32,7 @@
 #include "py/runtime0.h"
 #include "py/runtime.h"
 #include "py/stackctrl.h"
+#include "py/mperrno.h"
 #include "py/mphal.h"
 #include "py/gc.h"
 #include "lib/mp-readline/readline.h"
@@ -111,7 +112,7 @@ void user_init(void) {
 
 #if !MICROPY_VFS
 mp_lexer_t *mp_lexer_new_from_file(const char *filename) {
-    return NULL;
+    mp_raise_OSError(MP_ENOENT);
 }
 
 mp_import_stat_t mp_import_stat(const char *path) {