Reorder middleware error checking code

[synzhu]

We should check the error returned from libp2pNodeFactory before doing anything else

[huitseeker]

THanks!

[codecov-commenter]

Codecov Report

Merging #1331 (b61ecd0) into master (f3f78f5) will increase coverage by 0.02%.
The diff coverage is 0.00%.

@@            Coverage Diff             @@
##           master    #1331      +/-   ##
==========================================
+ Coverage   56.19%   56.21%   +0.02%     
==========================================
  Files         500      500              
  Lines       31072    31072              
==========================================
+ Hits        17460    17468       +8     
+ Misses      11247    11236      -11     
- Partials     2365     2368       +3     

Flag	Coverage Δ
unittests	56.21% <0.00%> (+0.02%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
network/p2p/middleware.go	0.00% <0.00%> (ø)
...sus/approvals/assignment_collector_statemachine.go	50.00% <0.00%> (+7.69%)	⬆️

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[huitseeker]

bors merge

[bors]

Build succeeded:

• Integration Tests (1.15)
• Integration Tests (1.16)
• Lint
• Unit Tests (1.15)
• Unit Tests (1.16)