qemu-arm: Move lexer constructors to within NLR handler block.

And raise an exception when mp_lexer_new_from_file is called.

qemu-arm/main.c

@@ -12,15 +12,12 @@
 #include "py/stackctrl.h"
 #include "py/gc.h"
 #include "py/repl.h"
+#include "py/mperrno.h"
 
 void do_str(const char *src, mp_parse_input_kind_t input_kind) {
-    mp_lexer_t *lex = mp_lexer_new_from_str_len(MP_QSTR__lt_stdin_gt_, src, strlen(src), 0);
-    if (lex == NULL) {
-        return;
-    }
-
     nlr_buf_t nlr;
     if (nlr_push(&nlr) == 0) {
+        mp_lexer_t *lex = mp_lexer_new_from_str_len(MP_QSTR__lt_stdin_gt_, src, strlen(src), 0);
         qstr source_name = lex->source_name;
         mp_parse_tree_t parse_tree = mp_parse(lex, input_kind);
         mp_obj_t module_fun = mp_compile(&parse_tree, source_name, MP_EMIT_OPT_NONE, true);
@@ -47,7 +44,7 @@ void gc_collect(void) {
 }
 
 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) {

qemu-arm/test_main.c

@@ -11,7 +11,7 @@
 #include "py/runtime.h"
 #include "py/stackctrl.h"
 #include "py/gc.h"
-#include "py/repl.h"
+#include "py/mperrno.h"
 
 #include "tinytest.h"
 #include "tinytest_macros.h"
@@ -24,13 +24,9 @@ inline void do_str(const char *src) {
     gc_init(heap, (char*)heap + HEAP_SIZE);
     mp_init();
 
-    mp_lexer_t *lex = mp_lexer_new_from_str_len(MP_QSTR__lt_stdin_gt_, src, strlen(src), 0);
-    if (lex == NULL) {
-        tt_abort_msg("Lexer initialization error");
-    }
-
     nlr_buf_t nlr;
     if (nlr_push(&nlr) == 0) {
+        mp_lexer_t *lex = mp_lexer_new_from_str_len(MP_QSTR__lt_stdin_gt_, src, strlen(src), 0);
         qstr source_name = lex->source_name;
         mp_parse_tree_t parse_tree = mp_parse(lex, MP_PARSE_FILE_INPUT);
         mp_obj_t module_fun = mp_compile(&parse_tree, source_name, MP_EMIT_OPT_NONE, false);
@@ -80,7 +76,7 @@ void gc_collect(void) {
 }
 
 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) {