Fix heuristics in get_app_caller_source_code_location (#862)

Author: wwwillchen

mesop/utils/caller.py

@@ -11,9 +11,14 @@ def get_app_caller_source_code_location() -> pb.SourceCodeLocation | None:
     caller_info = inspect.getframeinfo(current_frame)
     filename = caller_info.filename
     # "mesop/mesop" is the file path of the core Mesop framework when running under bazel.
+    # The exception is the examples subdir, which are Mesop apps and not actually part of
+    # the core Mesop framework.
+    #
     # "site-packages" is the file path of the Mesop framework when running under pip CLI.
     # If the file is neither of those paths, then we assume it is an app file.
-    if "mesop/mesop" not in filename and "site-packages" not in filename:
+    if (
+      "mesop/mesop" not in filename or "mesop/mesop/examples" in filename
+    ) and "site-packages" not in filename:
       # Get module from filepath
       splitted_file = filename.split("runfiles/")
       if len(splitted_file) < 2: