Hello Spine team,
I'm using spine beta 4.0.7 to legacy export file saved from 3.8.9 back to 3.7 and got this error log
can you guys help me to point out what's the problem here? Does it has anything to do with my file or it's just some compatibility issues?
Thank you very much!

[error] Error converting JSON to: 3.7
   at s.jBM._(_:103)
   at s.Rro._(_:618)
   at java.lang.Thread.run(Unknown Source)
Cause: [npe] Cannot invoke "String.equals(Object)" because "<local3>._" is null
   at s.amV._(_:159)
   at s.amV.<init>(_:136)
   at s.jBM._(_:98) ...
ERROR: Unable to export:
[error] Error converting JSON to: 3.7
   at s.jBM._(_:103)
   at s.Rro._(_:618)
   at java.lang.Thread.run(Unknown Source)
Cause: [npe] Cannot invoke "String.equals(Object)" because "<local3>._" is null
   at s.amV._(_:159)
   at s.amV.<init>(_:136)
   at s.jBM._(_:98) ...
ERROR: Unable to export:
[error] Error converting JSON to: 3.7
   at s.jBM._(_:103)
   at s.Rro._(_:618)
   at java.lang.Thread.run(Unknown Source)
Cause: [npe] Cannot invoke "String.equals(Object)" because "<local3>._" is null
   at s.amV._(_:159)
   at s.amV.<init>(_:136)
   at s.jBM._(_:98) ...
ERROR: Unable to export:
[error] Error converting JSON to: 3.7
   at s.jBM._(_:103)
   at s.Rro._(_:618)
   at java.lang.Thread.run(Unknown Source)
Cause: [npe] Cannot invoke "String.equals(Object)" because "<local3>._" is null
   at s.amV._(_:159)
   at s.amV.<init>(_:136)
   at s.jBM._(_:98) ...