add test for coverage

Author: yaacovCR

src/language/__tests__/lexer-test.ts

@@ -165,6 +165,13 @@ describe('Lexer', () => {
     });
   });
 
+  it('reports unexpected characters', () => {
+    expectSyntaxError('.').to.deep.equal({
+      message: 'Syntax Error: Unexpected character: ".".',
+      locations: [{ line: 1, column: 1 }],
+    });
+  });
+
   it('errors respect whitespace', () => {
     let caughtError;
     try {