fix: correct undefined toString function and nullable path variable (#97)

* fix: iOS release `toString()` build failure

* fix: RN 0.77,x  android nullability issue of `path.getString()`

Author: ian-wd

android/src/main/java/com/sourcetoad/reactnativesketchcanvas/RNTSketchCanvasManager.kt

@@ -133,9 +133,9 @@ class RNTSketchCanvasViewManager :
         if (path != null) {
             for (i in 0 until path.size()) {
                 val coor =
-                    path.getString(i).split(",".toRegex()).dropLastWhile { it.isEmpty() }
-                        .toTypedArray()
-                if (pointPath != null) {
+                    path.getString(i)?.split(",".toRegex())?.dropLastWhile { it.isEmpty() }
+                        ?.toTypedArray()
+                if (coor != null && pointPath != null) {
                     pointPath.add(PointF(coor[0].toFloat(), coor[1].toFloat()))
                 }
             }

ios/RNSketchCanvasViewComponent.mm

@@ -73,7 +73,7 @@ -(void)prepareForRecycle {
 
 - (NSDictionary*)RNTSketchCanvasTextStructToDict:(const RNTSketchCanvasTextStruct&)txt {
     return @{
-        @"text": RCTNSStringFromString(toString(txt.text)),
+        @"text": RCTNSStringFromString(txt.text),
         @"font": RCTNSStringFromString(txt.font),
         @"fontSize": @(txt.fontSize),
         @"fontColor": @(txt.fontColor),