Improve errorhandling on webserver endpoint

Part of https://github.com/freqtrade/frequi/issues/1387

freqtrade/rpc/api_server/api_v1.py

@@ -269,7 +269,10 @@ def pair_history(pair: str, timeframe: str, timerange: str, strategy: str,
         'timerange': timerange,
         'freqaimodel': freqaimodel if freqaimodel else config.get('freqaimodel'),
     })
-    return RPC._rpc_analysed_history_full(config, pair, timeframe, exchange)
+    try:
+        return RPC._rpc_analysed_history_full(config, pair, timeframe, exchange)
+    except Exception as e:
+        raise HTTPException(status_code=502, detail=str(e))
 
 
 @router.get('/plot_config', response_model=PlotConfig, tags=['candle data'])
@@ -284,7 +287,10 @@ def plot_config(strategy: Optional[str] = None, config=Depends(get_config),
         config1.update({
             'strategy': strategy
         })
+    try:
         return PlotConfig.parse_obj(RPC._rpc_plot_config_with_strategy(config1))
+    except Exception as e:
+        raise HTTPException(status_code=502, detail=str(e))
 
 
 @router.get('/strategies', response_model=StrategyListResponse, tags=['strategy'])

tests/rpc/test_rpc_apiserver.py

@@ -1476,6 +1476,12 @@ def test_api_pair_history(botclient, mocker):
                     "&timerange=20180111-20180112")
     assert_response(rc, 422)
 
+    # Invalid strategy
+    rc = client_get(client,
+                    f"{BASE_URI}/pair_history?pair=UNITTEST%2FBTC&timeframe={timeframe}"
+                    "&timerange=20180111-20180112&strategy={CURRENT_TEST_STRATEGY}11")
+    assert_response(rc, 502)
+
     # Working
     rc = client_get(client,
                     f"{BASE_URI}/pair_history?pair=UNITTEST%2FBTC&timeframe={timeframe}"
@@ -1510,8 +1516,7 @@ def test_api_pair_history(botclient, mocker):
                     f"{BASE_URI}/pair_history?pair=UNITTEST%2FBTC&timeframe={timeframe}"
                     f"&timerange=20200111-20200112&strategy={CURRENT_TEST_STRATEGY}")
     assert_response(rc, 502)
-    assert rc.json()['error'] == ("Error querying /api/v1/pair_history: "
+    assert rc.json()['detail'] == ("No data for UNITTEST/BTC, 5m in 20200111-20200112 found.")
-                                  "No data for UNITTEST/BTC, 5m in 20200111-20200112 found.")
 
 
 def test_api_plot_config(botclient, mocker):
@@ -1548,6 +1553,10 @@ def test_api_plot_config(botclient, mocker):
     assert_response(rc)
     assert rc.json()['subplots'] == {}
 
+    rc = client_get(client, f"{BASE_URI}/plot_config?strategy=NotAStrategy")
+    assert_response(rc, 502)
+    assert rc.json()['detail'] is not None
+
     mocker.patch('freqtrade.rpc.api_server.api_v1.get_rpc_optional', return_value=None)
 
     rc = client_get(client, f"{BASE_URI}/plot_config")