test: add test for set_option errors

Author: jrr6

tests/lean/run/setOptionErrors.lean

@@ -0,0 +1,20 @@
+/-!
+# `set_option` Errors
+
+Tests the error messages produced by the `set_option` command.
+-/
+
+/-- error: Unknown option `nonexistent_option_name` -/
+#guard_msgs in
+set_option nonexistent_option_name false
+
+/--
+error: set_option value type mismatch: The value
+  21
+has type
+  Nat
+but the option `pp.explicit` expects a value of type
+  Bool
+-/
+#guard_msgs in
+set_option pp.explicit 21