inspect kwargs for better errors

strax/context.py

@@ -1122,6 +1122,10 @@ def get_array(self, run_id: ty.Union[str, tuple, list],
         {get_docs}
         """
         run_ids = strax.to_str_tuple(run_id)
+
+        if kwargs.get('allow_multiple', False):
+            raise RuntimeError('Cannot allow_multiple with get_array/get_df')
+
         if len(run_ids) > 1:
             results = strax.multi_run(
                 self.get_array, run_ids, targets=targets,
@@ -1132,7 +1136,6 @@ def get_array(self, run_id: ty.Union[str, tuple, list],
                 targets,
                 save=save,
                 max_workers=max_workers,
-                allow_multiple=False,
                 **kwargs)
             results = [x.data for x in source]
 
@@ -1183,6 +1186,9 @@ def accumulate(self,
                 n_chunks: number of chunks in run
                 n_rows: number of data entries in run
         """
+        if kwargs.get('allow_multiple', False):
+            raise RuntimeError('Cannot allow_multiple with accumulate')
+
         n_chunks = 0
         seen_data = False
         result = {'n_rows': 0}
@@ -1194,7 +1200,6 @@ def function(arr):
             function_takes_fields = False
 
         for chunk in self.get_iter(run_id, targets,
-                                   allow_multiple=False,
                                    **kwargs):
             data = chunk.data
             data = self._apply_function(data, targets)

tests/test_core.py

@@ -421,7 +421,7 @@ def test_allow_multiple(targets=('peaks', 'records')):
                 function(run_id=run_id,
                          allow_multiple=True,
                          targets=targets)
-            except TypeError:
+            except RuntimeError:
                 # Great, this doesn't work (and it shouldn't!)
                 continue
             raise ValueError(f'{function} could run with allow_multiple')