evm: make #setMode an InternalOp so its handled by exceptions

Author: Everett Hildenbrandt

evm.md

@@ -170,10 +170,9 @@ Our semantics is modal, with the initial mode being set on the command line via
 -   `#setMode_` sets the mode to the supplied one.
 
 ```k
-    syntax Mode ::= "#setMode" Mode
- // -------------------------------
+    syntax InternalOp ::= "#setMode" Mode
+ // -------------------------------------
     rule <k> #setMode EXECMODE => . ... </k> <mode> _ => EXECMODE </mode>
-    rule <k> EX:Exception ~> (#setMode _ => .) ... </k>
 ```
 
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