Add code snippet to error message

index.js

@@ -101,15 +101,17 @@ function handle(input) {
 
 
 function apply(json) {
-  let output
+  let output = json
 
-  try {
-    output = args.reduce(reduce, json)
-  } catch (e) {
-    if (e !== std.skip) {
-      throw e
-    } else {
-      return
+  for (let [i, code] of args.entries()) {
+    try {
+      output = reduce(output, code)
+    } catch (e) {
+      if (e === std.skip) {
+        return
+      }
+      stderr.write(`${snippet(i, code)}\n${e.stack || e}\n`)
+      process.exit(1)
     }
   }
 
@@ -122,3 +124,16 @@ function apply(json) {
     console.log(text)
   }
 }
+
+function snippet(i, code) {
+  let pre = args.slice(0, i).join(' ')
+  let post = args.slice(i + 1).join(' ')
+  if (pre.length > 20) {
+    pre = '...' + pre.substring(pre.length - 20)
+  }
+  if (post.length > 20) {
+    post = post.substring(0, 20) + '...'
+  }
+  const chalk = require('chalk')
+  return `\n  ${pre} ${chalk.red.underline(code)} ${post}\n`
+}