Fix references to private _plugins data property

src/BaseCharts/Bar.js

@@ -77,7 +77,7 @@ export default {
 
   methods: {
     addPlugin (plugin) {
-      this._plugins.push(plugin)
+      this.$data._plugins.push(plugin)
     },
     renderChart (data, options) {
       let chartOptions = mergeOptions(this.defaultOptions, options)
@@ -86,7 +86,7 @@ export default {
           type: 'bar',
           data: data,
           options: chartOptions,
-          plugins: this._plugins
+          plugins: this.$data._plugins
         }
       )
     }

src/BaseCharts/Bubble.js

@@ -79,7 +79,7 @@ export default {
 
   methods: {
     addPlugin (plugin) {
-      this._plugins.push(plugin)
+      this.$data._plugins.push(plugin)
     },
     renderChart (data, options) {
       let chartOptions = mergeOptions(this.defaultOptions, options)
@@ -89,7 +89,7 @@ export default {
           type: 'bubble',
           data: data,
           options: chartOptions,
-          plugins: this._plugins
+          plugins: this.$data._plugins
         }
       )
     }

src/BaseCharts/Doughnut.js

@@ -62,7 +62,7 @@ export default {
 
   methods: {
     addPlugin (plugin) {
-      this._plugins.push(plugin)
+      this.$data._plugins.push(plugin)
     },
     renderChart (data, options) {
       let chartOptions = mergeOptions(this.defaultOptions, options)
@@ -72,7 +72,7 @@ export default {
           type: 'doughnut',
           data: data,
           options: chartOptions,
-          plugins: this._plugins
+          plugins: this.$data._plugins
         }
       )
     }

src/BaseCharts/HorizontalBar.js

@@ -79,7 +79,7 @@ export default {
 
   methods: {
     addPlugin (plugin) {
-      this._plugins.push(plugin)
+      this.$data._plugins.push(plugin)
     },
     renderChart (data, options, type) {
       let chartOptions = mergeOptions(this.defaultOptions, options)
@@ -88,7 +88,7 @@ export default {
           type: 'horizontalBar',
           data: data,
           options: chartOptions,
-          plugins: this._plugins
+          plugins: this.$data._plugins
         }
       )
     }

src/BaseCharts/Line.js

@@ -77,7 +77,7 @@ export default {
 
   methods: {
     addPlugin (plugin) {
-      this._plugins.push(plugin)
+      this.$data._plugins.push(plugin)
     },
     renderChart (data, options) {
       let chartOptions = mergeOptions(this.defaultOptions, options)
@@ -87,7 +87,7 @@ export default {
           type: 'line',
           data: data,
           options: chartOptions,
-          plugins: this._plugins
+          plugins: this.$data._plugins
         }
       )
     }

src/BaseCharts/Pie.js

@@ -62,7 +62,7 @@ export default {
 
   methods: {
     addPlugin (plugin) {
-      this._plugins.push(plugin)
+      this.$data._plugins.push(plugin)
     },
     renderChart (data, options) {
       let chartOptions = mergeOptions(this.defaultOptions, options)
@@ -72,7 +72,7 @@ export default {
           type: 'pie',
           data: data,
           options: chartOptions,
-          plugins: this._plugins
+          plugins: this.$data._plugins
         }
       )
     }

src/BaseCharts/PolarArea.js

@@ -62,7 +62,7 @@ export default {
 
   methods: {
     addPlugin (plugin) {
-      this._plugins.push(plugin)
+      this.$data._plugins.push(plugin)
     },
     renderChart (data, options) {
       let chartOptions = mergeOptions(this.defaultOptions, options)
@@ -72,7 +72,7 @@ export default {
           type: 'polarArea',
           data: data,
           options: chartOptions,
-          plugins: this._plugins
+          plugins: this.$data._plugins
         }
       )
     }

src/BaseCharts/Radar.js

@@ -62,7 +62,7 @@ export default {
 
   methods: {
     addPlugin (plugin) {
-      this._plugins.push(plugin)
+      this.$data._plugins.push(plugin)
     },
     renderChart (data, options) {
       let chartOptions = mergeOptions(this.defaultOptions, options)
@@ -72,7 +72,7 @@ export default {
           type: 'radar',
           data: data,
           options: chartOptions,
-          plugins: this._plugins
+          plugins: this.$data._plugins
         }
       )
     }

src/BaseCharts/Scatter.js

@@ -68,7 +68,7 @@ export default {
 
   methods: {
     addPlugin (plugin) {
-      this._plugins.push(plugin)
+      this.$data._plugins.push(plugin)
     },
     renderChart (data, options) {
       let chartOptions = mergeOptions(this.defaultOptions, options)
@@ -78,7 +78,7 @@ export default {
           type: 'scatter',
           data: data,
           options: chartOptions,
-          plugins: this._plugins
+          plugins: this.$data._plugins
         }
       )
     }