Fix issues with out of index code (#1545)

mythril/laser/ethereum/state/global_state.py

@@ -97,7 +97,7 @@ class GlobalState:
         instructions = self.environment.code.instruction_list
         try:
             return instructions[self.mstate.pc]
-        except KeyError:
+        except IndexError:
             return {"address": self.mstate.pc, "opcode": "STOP"}
 
     @property

mythril/laser/plugin/plugins/coverage/coverage_plugin.py

@@ -49,7 +49,10 @@ class InstructionCoveragePlugin(LaserPlugin):
         def stop_sym_exec_hook():
             # Print results
             for code, code_cov in self.coverage.items():
-                cov_percentage = sum(code_cov[1]) / float(code_cov[0]) * 100
+                if sum(code_cov[1]) == 0 and code_cov[0] == 0:
+                    cov_percentage = 0
+                else:
+                    cov_percentage = sum(code_cov[1]) / float(code_cov[0]) * 100
 
                 log.info(
                     "Achieved {:.2f}% coverage for code: {}".format(
@@ -70,7 +73,10 @@ class InstructionCoveragePlugin(LaserPlugin):
                     number_of_instructions,
                     [False] * number_of_instructions,
                 )
-
+            if global_state.mstate.pc >= len(self.coverage[code][1]):
+                # Instruction beyond the instruction list are considered as STOP by EVM
+                # and can be ignored
+                return
             self.coverage[code][1][global_state.mstate.pc] = True
 
         @symbolic_vm.laser_hook("start_sym_trans")