title: uglify js error unexpected token eof "undefined"
body: <p>So I installed npm using npm install uglify-js</p>
  
  <p>I run a command which is:</p>
  
  <pre><code>cat file1.js file2.js .. fileN.js | uglifyjs -o files.min.js
  </code></pre>
  
  <p>and I get this error:</p>
  
  <pre><code>WARN: ERROR: Unexpected token eof «undefined», expected punc «,» [-:630,15]
  
  /usr/local/lib/node_modules/uglify-js/lib/parse.js:199
      throw new JS_Parse_Error(message, line, col, pos);
            ^
  Error
      at new JS_Parse_Error (/usr/local/lib/node_modules/uglify-js/lib/parse.js:185:18)
      at js_error (/usr/local/lib/node_modules/uglify-js/lib/parse.js:199:11)
      at croak (/usr/local/lib/node_modules/uglify-js/lib/parse.js:630:9)
      at token_error (/usr/local/lib/node_modules/uglify-js/lib/parse.js:638:9)
      at expect_token (/usr/local/lib/node_modules/uglify-js/lib/parse.js:651:9)
      at expect (/usr/local/lib/node_modules/uglify-js/lib/parse.js:654:36)
      at ctor.argnames (/usr/local/lib/node_modules/uglify-js/lib/parse.js:897:52)
      at function_ (/usr/local/lib/node_modules/uglify-js/lib/parse.js:902:15)
      at expr_atom (/usr/local/lib/node_modules/uglify-js/lib/parse.js:1114:24)
      at maybe_unary (/usr/local/lib/node_modules/uglify-js/lib/parse.js:1278:19)
  </code></pre>
  
  <p>Any ideas on what this is about or how I should go about fixing it?</p>