store error in progress

unwind/models.py

@@ -153,6 +153,34 @@ class Progress:
     started: datetime = field(default_factory=utcnow)
     stopped: Optional[str] = None
 
+    @property
+    def _state(self) -> dict:
+        return json.loads(self.state or "{}")
+
+    @_state.setter
+    def _state(self, state: dict):
+        self.state = json.dumps(state, separators=(",", ":"))
+
+    @property
+    def percent(self) -> float:
+        return self._state["percent"]
+
+    @percent.setter
+    def percent(self, percent: float):
+        state = self._state
+        state["percent"] = percent
+        self._state = state
+
+    @property
+    def error(self) -> str:
+        return self._state.get("error", "")
+
+    @error.setter
+    def error(self, error: str):
+        state = self._state
+        state["error"] = error
+        self._state = state
+
 
 @dataclass
 class Movie: