REF: Fix typo

Author: kernc

backtesting/backtesting.py

@@ -142,7 +142,7 @@ def init():
         if not is_arraylike or not 1 <= value.ndim <= 2 or value.shape[-1] != len(self._data.Close):
             raise ValueError(
                 'Indicators must return (optionally a tuple of) numpy.arrays of same '
-                f'length as `data` (data shape: {self._data.Close.shape}; indicator "{name}"'
+                f'length as `data` (data shape: {self._data.Close.shape}; indicator "{name}" '
                 f'shape: {getattr(value, "shape" , "")}, returned value: {value})')
 
         if plot and overlay is None and np.issubdtype(value.dtype, np.number):