[SMTChecker] Fix internal error on try/catch

test/libsolidity/smtCheckerTests/control_flow/try_catch_1.sol

@@ -0,0 +1,12 @@
+pragma experimental SMTChecker;
+contract C {
+	function g() public returns (uint) {
+		try this.g() returns (uint x) { x; }
+		catch Error(string memory s) { s; }
+	}
+}
+// ====
+// EVMVersion: >=byzantium
+// ----
+// Warning: (98-121): Assertion checker does not support try/catch clauses.
+// Warning: (124-159): Assertion checker does not support try/catch clauses.

test/libsolidity/smtCheckerTests/control_flow/try_catch_2.sol

@@ -0,0 +1,14 @@
+pragma experimental SMTChecker;
+contract C {
+	function f() public {
+		try this.f() {}
+		catch (bytes memory x) {
+			x;
+		}
+	}
+}
+// ====
+// EVMVersion: >=byzantium
+// ----
+// Warning: (83-85): Assertion checker does not support try/catch clauses.
+// Warning: (88-122): Assertion checker does not support try/catch clauses.