[Bugfix] Prevent panic when external contract query executed

[yun-yeo]

Summary of changes

External contract query, which is causing out-of-gas, also causes core node panic.
In this PR, I added recover statement to prevent panic from the out-of-gas error.

close #431

Report of required housekeeping

• Github issue OR spec proposal link
• Wrote tests
• Updated API documentation (client/lcd/swagger-ui/swagger.yaml)
• Added a relevant changelog entry: clog add [section] [stanza] [message]

---

(FOR ADMIN) Before merging

• Added appropriate labels to PR
• Squashed all commits, uses message "Merge pull request #XYZ: [title]" (coding standards)
• Confirm added tests are consistent with the intended behavior of changes
• Ensure all tests pass

[codecov]

Codecov Report

Merging #432 (32bfb4d) into develop (d3c4751) will decrease coverage by 0.00%.
The diff coverage is 70.00%.

@@             Coverage Diff             @@
##           develop     #432      +/-   ##
===========================================
- Coverage    67.52%   67.52%   -0.01%     
===========================================
  Files          117      117              
  Lines         5053     5071      +18     
===========================================
+ Hits          3412     3424      +12     
- Misses        1427     1433       +6     
  Partials       214      214              

Impacted Files	Coverage Δ
x/wasm/internal/keeper/querier.go	33.73% <70.00%> (+9.11%)	⬆️