Move debug to devDependencies

package.json

@@ -55,6 +55,7 @@
     "chai": "^4.2.0",
     "chai-as-promised": "^7.1.1",
     "colors": "~1.3.3",
+    "debug": "^4.1.1",
     "dirty-chai": "2.0.1",
     "mocha": "^6.0.2",
     "perfy": "^1.1.5",
@@ -65,7 +66,6 @@
   },
   "dependencies": {
     "clone": "^2.1.2",
-    "debug": "^4.1.1",
     "events": "^3.0.0",
     "lodash.isobjectlike": "^4.0.0",
     "object-hash": "^1.3.1",

src/almanac.js

@@ -3,11 +3,11 @@
 import Fact from './fact'
 import { UndefinedFactError } from './errors'
 
-let debug = require('debug')('json-rules-engine')
-let verbose = require('debug')('json-rules-engine-verbose')
+let debug = require('./debugger')('json-rules-engine')
+let verbose = require('./debugger')('json-rules-engine-verbose')
 let selectn = require('selectn')
 let isObjectLike = require('lodash.isobjectlike')
-let warn = require('debug')('json-rules-engine:warn')
+let warn = require('./debugger')('json-rules-engine:warn')
 
 /**
  * Fact results lookup

src/condition.js

@@ -1,6 +1,6 @@
 'use strict'
 
-let debug = require('debug')('json-rules-engine')
+let debug = require('./debugger')('json-rules-engine')
 let isObjectLike = require('lodash.isobjectlike')
 
 export default class Condition {

src/debugger.js

@@ -0,0 +1,7 @@
+module.exports = function (name) {
+  try {
+    return require('debug')(name)
+  } catch (e) {
+    return function () {}
+  }
+}

src/engine.js

@@ -8,7 +8,7 @@ import { EventEmitter } from 'events'
 import { SuccessEventFact } from './engine-facts'
 import defaultOperators from './engine-default-operators'
 
-let debug = require('debug')('json-rules-engine')
+let debug = require('./debugger')('json-rules-engine')
 
 export const READY = 'READY'
 export const RUNNING = 'RUNNING'

src/fact.js

@@ -2,7 +2,7 @@
 
 import hash from 'object-hash'
 
-let verbose = require('debug')('json-rules-engine-verbose')
+let verbose = require('./debugger')('json-rules-engine-verbose')
 
 class Fact {
   /**

src/rule.js

@@ -4,7 +4,7 @@ import Condition from './condition'
 import RuleResult from './rule-result'
 import { EventEmitter } from 'events'
 
-let debug = require('debug')('json-rules-engine')
+let debug = require('./debugger')('json-rules-engine')
 
 class Rule extends EventEmitter {
   /**