chore: add more friendly warnings

ast/error.go

@@ -79,7 +79,7 @@ func (self SyntaxError) description() string {
 
     /* check for empty source */
     if self.Src == "" {
-        return fmt.Sprintf("no sources available: %#v", self)
+        return fmt.Sprintf("no sources available, the input json is empty: %#v", self)
     }
 
     /* prevent slicing before the beginning */

internal/decoder/errors/errors.go

@@ -46,7 +46,7 @@ func (self SyntaxError) Description() string {
 func (self SyntaxError) description() string {
     /* check for empty source */
     if self.Src == "" {
-        return fmt.Sprintf("no sources available: %#v", self)
+        return fmt.Sprintf("no sources available, the input json is empty: %#v", self)
     }
 
     p, x, q, y := calcBounds(len(self.Src), self.Pos)

internal/encoder/vars/errors.go

@@ -58,7 +58,7 @@ const (
 func GoPanic(code int, val unsafe.Pointer) {
     switch(code){
     case PanicNilPointerOfNonEmptyString:
-        panic(fmt.Sprintf("val: %#v has nil pointer while its length is not zero!", (*rt.GoString)(val)))
+        panic(fmt.Sprintf("val: %#v has nil pointer while its length is not zero!\nThis is a nil pointer exception (NPE) problem. There might be a data race issue. It is recommended to execute the tests related to the code with the `-race` compile flag to detect the problem.", (*rt.GoString)(val)))
     default:
         panic("encoder error!")
     }