Fix carriage-return logging when the buffer is empty

app/logger.py

@@ -64,7 +64,7 @@ def write(self, data):
 
             # Simple handling for cr to overwrite the last output if it isnt a full line
             # else logs just get full of progress messages
-            if isinstance(data, str) and data.startswith("\r") and not logs[-1]["m"].endswith("\n"):
+            if isinstance(data, str) and data.startswith("\r") and logs and not logs[-1]["m"].endswith("\n"):
                 logs.pop()
             logs.append(entry)
         super().write(data)

tests-unit/app_test/logger_test.py

@@ -0,0 +1,15 @@
+from collections import deque
+import io
+
+import app.logger
+
+
+def test_carriage_return_can_be_first_log_entry(monkeypatch):
+    monkeypatch.setattr(app.logger, "logs", deque())
+    stream = io.TextIOWrapper(io.BytesIO(), encoding="utf-8")
+    interceptor = app.logger.LogInterceptor(stream)
+
+    interceptor.write("\rprogress")
+
+    assert len(app.logger.logs) == 1
+    assert app.logger.logs[0]["m"] == "\rprogress"