Command line: Fix for uncaught errors for empty 'commandLine' object. (#1862)

This fixes the issue that the Command line plugin throws an error when the 'commandLine' object is not defined/an empty object. This always happens when an element with no text is highlighted.

Author: libantema

plugins/command-line/prism-command-line.js

@@ -79,7 +79,7 @@ Prism.hooks.add('before-insert', function (env) {
 
 	// Reinsert the output lines into the highlighted code. -- cwells
 	var codeLines = env.highlightedCode.split('\n');
-	for (var i = 0; i < commandLine.outputLines.length; i++) {
+	for (var i = 0, l = (commandLine.outputLines || []).length; i < l; i++) {
 		if (commandLine.outputLines.hasOwnProperty(i)) {
 			codeLines[i] = commandLine.outputLines[i];
 		}
@@ -107,7 +107,7 @@ Prism.hooks.add('complete', function (env) {
 	};
 
 	// Create the "rows" that will become the command-line prompts. -- cwells
-	var promptLines = new Array(commandLine.numberOfLines + 1);
+	var promptLines = new Array((commandLine.numberOfLines || 0) + 1);
 	var promptText = getAttribute('data-prompt', '');
 	if (promptText !== '') {
 		promptLines = promptLines.join('<span data-prompt="' + promptText + '"></span>');
@@ -123,7 +123,7 @@ Prism.hooks.add('complete', function (env) {
 	prompt.innerHTML = promptLines;
 
 	// Remove the prompt from the output lines. -- cwells
-	for (var i = 0; i < commandLine.outputLines.length; i++) {
+	for (var i = 0, l = (commandLine.outputLines || []).length; i < l; i++) {
 		if (commandLine.outputLines.hasOwnProperty(i)) {
 			var node = prompt.children[i];
 			node.removeAttribute('data-user');