added 'check' in matching

Author: lfarv

pyat/at/latticetools/matching.py

@@ -36,6 +36,7 @@ def fun(vals):
     bounds = np.array([var.bounds for var in variables])
 
     constraints.evaluate(ring, initial=True, dp=dp, dct=dct, df=df)
+    constraints.check()
     ntargets = constraints.flat_values.size
 
     if method is None:

pyat/at/latticetools/observables.py

@@ -527,7 +527,7 @@ def check(self):
         ok = super().check()
         shp = self._shape
         if ok and shp and shp[0] <= 0:
-            raise AtError(f"{self.name}: No location selected in the lattice.")
+            raise AtError(f"Observable {self.name!r}: No location selected in the lattice.")
         return ok
 
     def _all_lines(self):