Merge pull request #6442 from busykai/fix-6441

Fix #6441.

Author: ingorichter

src/language/CodeInspection.js

@@ -311,13 +311,14 @@ define(function (require, exports, module) {
 
                     if (inspectionResult.result) {
                         inspectionResult.result.errors.forEach(function (error) {
-                            // some inspectors don't always provide a line number
-                            if (!isNaN(error.pos.line)) {
+                            // some inspectors don't always provide a line number or report a negative line number
+                            if (!isNaN(error.pos.line) &&
+                                    (error.pos.line + 1) > 0 &&
+                                    (error.codeSnippet = currentDoc.getLine(error.pos.line)) !== undefined) {
                                 error.friendlyLine = error.pos.line + 1;
-                                error.codeSnippet = currentDoc.getLine(error.pos.line);
                                 error.codeSnippet = error.codeSnippet.substr(0, Math.min(175, error.codeSnippet.length));  // limit snippet width
-                            }
-
+                            } 
+                            
                             if (error.type !== Type.META) {
                                 numProblems++;
                             }