instantiating an Evaluator without one or more AbstractModel instance…

…s now raises a type error

ema_workbench/em_framework/evaluators.py

@@ -111,6 +111,11 @@ def __init__(self, msis):
 
         if isinstance(msis, AbstractModel):
             msis = [msis]
+        else:
+            for entry in msis:
+                if not isinstance(entry, AbstractModel):
+                    raise TypeError((f"{entry} should be an AbstractModel "
+                                     f"instance but is a {entry.__class__} instance"))
 
         self._msis = msis
         self.callback = None
@@ -274,7 +279,6 @@ def robust_optimize(
 
 
 class SequentialEvaluator(BaseEvaluator):
-
     def initialize(self):
         pass
 
@@ -790,4 +794,4 @@ def robust_optimize(
         convergence_freq,
         logging_freq,
         **kwargs,
-    )
+    )