show liniting syntax errors

SQUASHED: AUTO-COMMIT-demos-javascript-double-import.js,AUTO-COMMIT-src-external-eslint-eslint-lint.js,

demos/javascript/double-import.js

@@ -1,4 +1,5 @@
 import {value} from "./a.js"
+import {value} from "./a.js"
 
 
 var foo =3

src/external/eslint/eslint-lint.js

@@ -343,7 +343,7 @@ import {parse} from "./eslint-parser.js";
       var error = errors[i];
       result.push({message: error.message,
                  severity: getSeverity(error),
-                 from: getPos(error, true),
+                 from: getPos(error, true) ,
                    to: getPos(error, false)});	
     }
     return result;	  
@@ -352,6 +352,8 @@ import {parse} from "./eslint-parser.js";
   CodeMirror.registerHelper("lint", "javascript", validator);
 
   function getPos(error, from) {
+    if (error.line === undefined) return CodeMirror.Pos(0, 0)
+
     var line = error.line-1, ch = from ? error.column : error.column+1;
     if (error.node && error.node.loc) {
       line = from ? error.node.loc.start.line -1 : error.node.loc.end.line -1;