Add better error messages

index.js

@@ -3,11 +3,9 @@
 const os = require('os')
 const fs = require('fs')
 const path = require('path')
-const JSON = require('lossless-json')
+const JSON = require('./json')
 const std = require('./std')
 
-JSON.config({circularRefs: false})
-
 try {
   require(path.join(os.homedir(), '.fxrc')) // Should be required before config.js usage.
 } catch (err) {
@@ -91,7 +89,13 @@ function handle(input) {
     args.shift()
   }
 
-  const json = JSON.parse(input)
+  let json
+  try {
+    json = JSON.parse(input)
+  } catch (e) {
+    printError(e, input)
+    process.exit(1)
+  }
 
   if (args.length === 0 && stdout.isTTY) {
     require('./fx')(filename, json)
@@ -101,7 +105,6 @@ function handle(input) {
   apply(json)
 }
 
-
 function apply(json) {
   let output = json
 
@@ -139,3 +142,33 @@ function snippet(i, code) {
   const chalk = require('chalk')
   return `\n  ${pre} ${chalk.red.underline(code)} ${post}\n`
 }
+
+function printError(e, input) {
+  if (e.char) {
+    let lineNumber = 1, start = e.char - 70, end = e.char + 50
+    if (start < 0) start = 0
+    if (end > input.length) end = input.length
+
+    for (let i = 0; i < input.length && i < start; i++) {
+      if (input[i] === '\n') lineNumber++
+    }
+
+    let lines = input
+      .substring(start, end)
+      .split('\n')
+
+    if (lines.length > 1) {
+      lines = lines.slice(1)
+      lineNumber++
+    }
+
+    const chalk = require('chalk')
+    process.stderr.write(`\n`)
+    for (let line of lines) {
+      process.stderr.write(`  ${chalk.yellow(lineNumber)}  ${line}\n`)
+      lineNumber++
+    }
+    process.stderr.write(`\n`)
+  }
+  process.stderr.write(e.toString() + '\n')
+}

json.js

@@ -0,0 +1,4 @@
+'use strict'
+const LosslessJSON = require('lossless-json')
+LosslessJSON.config({circularRefs: false})
+module.exports.parse = LosslessJSON.parse

package.json

@@ -48,14 +48,14 @@
   },
   "dependencies": {
     "@medv/blessed": "^2.0.1",
-    "chalk": "^3.0.0",
+    "chalk": "^4.1.0",
     "indent-string": "^4.0.0",
-    "lossless-json": "^1.0.3",
+    "lossless-json": "^1.0.4",
     "string-width": "^4.2.0"
   },
   "devDependencies": {
-    "ava": "^2.4.0",
-    "pkg": "^4.4.2",
-    "release-it": "^12.4.3"
+    "ava": "^3.9.0",
+    "pkg": "^4.4.8",
+    "release-it": "^13.6.3"
   }
 }

stream.js

@@ -1,5 +1,5 @@
 'use strict'
-const JSON = require('lossless-json')
+const JSON = require('./json')
 
 function apply(cb, input) {
   let json