better error message for writing not lists

lib/index.js

@@ -15,20 +15,29 @@ var formatters = {
     return JSON.stringify(file)
   },
   csv: function (file) {
+    if (!_.isArray(file)) {
+      reporters.notListError('csv')
+    }
     try {
       return dsv.csv.format(file)
     } catch (err) {
       reporters.parseError('csv')
     }
   },
   tsv: function (file) {
+    if (!_.isArray(file)) {
+      reporters.notListError('tsv')
+    }
     try {
       return dsv.tsv.format(file)
     } catch (err) {
       reporters.parseError('tsv')
     }
   },
   psv: function (file) {
+    if (!_.isArray(file)) {
+      reporters.notListError('psv')
+    }
     try {
       return dsv.dsv('|').format(file)
     } catch (err) {
@@ -90,6 +99,10 @@ reporters.parseError = function (format) {
   throw new Error(chalk.red('Error converting your data to ' + chalk.bold(format) + '.') + '\n\n' + chalk.cyan('Your data most likely contains objects or lists. Object values can only be strings for this format. Please convert before writing to file.\n'))
 }
 
+reporters.notListError = function (format) {
+  throw new Error(chalk.red('You passed in an object but converting to ' + chalk.bold(format) + ' requires a list of objects.') + chalk.cyan('\nIf you would like to write a one-row csv, put your object in a list like so: ' + chalk.bold('[data]')+'\n'))
+}
+
 /** @namespace */
 var helpers = {}