fix(state): fixing panic when err != nil but response is nil

[distractedm1nd]

There was a panic when err != nil but response == nil, for example in the case of: rpc error: code = NotFound desc = account celestia1gchva5av4v798xmqttln9qw9smzrjm2cv2q8e7 not found

2023-06-07T14:20:38.731+0200	ERROR	rpc	go-jsonrpc@v0.3.1/handler.go:276	panic in rpc method 'blob.Submit': runtime error: invalid memory address or nil pointer dereference

[codecov-commenter]

Codecov Report

Merging #2339 (ad8ddf2) into main (b046184) will decrease coverage by 0.03%.
The diff coverage is 0.00%.

@@            Coverage Diff             @@
##             main    #2339      +/-   ##
==========================================
- Coverage   50.90%   50.88%   -0.03%     
==========================================
  Files         154      154              
  Lines        9746     9746              
==========================================
- Hits         4961     4959       -2     
- Misses       4352     4353       +1     
- Partials      433      434       +1     

Impacted Files	Coverage Δ
state/core_access.go	27.53% <0.00%> (ø)

... and 3 files with indirect coverage changes

[Wondertan]

The cosmos sdk API is very weird and ambiguous sometimes.