Raising error when incompatible inputs are passed to mitigation

qiskit/ignis/mitigation/measurement/filters.py

@@ -108,6 +108,11 @@ def apply(self,
         # check forms of raw_data
         if isinstance(raw_data, dict):
             # counts dictionary
+            for data_label in raw_data.keys():
+                if data_label not in self._state_labels:
+                    raise QiskitError("Unexpected state label '" + data_label +
+                                      "', verify the fitter's state labels "
+                                      "correpsond to the input data")
             data_format = 0
             # convert to form2
             raw_data2 = [np.zeros(len(self._state_labels), dtype=float)]

releasenotes/notes/mitigtion-label-error-137dd0acfdcfc5f6.yaml

@@ -0,0 +1,4 @@
+---
+fixes:
+  - |
+    Raises `QiskitError` when using incorrect labels in measurement mitigation.