Add additional number lexing test

Author: leebyron

src/language/__tests__/lexer-test.js

@@ -574,6 +574,13 @@ describe('Lexer', () => {
       'expected digit but got: <EOF>.'
     );
 
+    expect(
+      () => lexOne('1.e1')
+    ).to.throw(
+      'Syntax Error GraphQL request (1:3) Invalid number, ' +
+      'expected digit but got: "e".'
+    );
+
     expect(
       () => lexOne('.123')
     ).to.throw(