[FIX, TESTING] Fix example code tester (hedyorg#4083)

* when a level misses example code, the example code of the previous level is tested (leading to issues)

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

---------

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

tests/test_snippets/test_adventures.py

@@ -77,25 +77,25 @@ def collect_snippets(path, filtered_language=None):
                             # Code snippets inside example code
                             try:
                                 example_code = utils.markdown_to_html_tags(level['example_code'])
+                                for tag in example_code:
+                                    if tag.name != 'pre' or not tag.contents[0]:
+                                        continue
+                                    code_snippet_counter += 1
+                                    try:
+                                        code = tag.contents[0].contents[0]
+                                    except BaseException:
+                                        print("Code container is empty...")
+                                        continue
+
+                                    snippet = Snippet(
+                                        filename=f,
+                                        level=level_number,
+                                        field_name=adventure_name + ' snippet #' + str(code_snippet_counter),
+                                        code=code,
+                                        adventure_name=adventure_name)
+                                    Hedy_snippets.append(snippet)
                             except Exception as E:
                                 print(E)
-                            for tag in example_code:
-                                if tag.name != 'pre' or not tag.contents[0]:
-                                    continue
-                                code_snippet_counter += 1
-                                try:
-                                    code = tag.contents[0].contents[0]
-                                except BaseException:
-                                    print("Code container is empty...")
-                                    continue
-
-                                snippet = Snippet(
-                                    filename=f,
-                                    level=level_number,
-                                    field_name=adventure_name + ' snippet #' + str(code_snippet_counter),
-                                    code=code,
-                                    adventure_name=adventure_name)
-                                Hedy_snippets.append(snippet)
 
     return Hedy_snippets
 
@@ -106,7 +106,7 @@ def collect_snippets(path, filtered_language=None):
 Hedy_snippets = [(s.name, s) for s in collect_snippets(path='../../content/adventures',
                                                        filtered_language=filtered_language)]
 #
-# level = 3
+# level = 4
 if level:
     Hedy_snippets = [(name, snippet) for (name, snippet) in Hedy_snippets if snippet.level == level]