prettify error message for catch-all conflict with existing path segment

[SericaLaw]

Hi, I find that the conflict message for catch-all wildcard with existing path segment is not clear enough during my use of gin framework, i.e. it only suggests that there is a conflict, but gives no hint about where the conflict is.

This PR will give a more user-friendly error message when users are trying to add two conflict routes as bellow:

r := New()
r.GET("/foo/bar", nil)
r.GET("/foo/*bar", nil)

Error message before:

catch-all conflicts with existing handle for the path segment root in path '/foo/*bar' 

Error message now:

catch-all wildcard '*bar' in new path '/foo/*bar' conflicts with existing path segment 'bar' in existing prefix '/foo/bar'

[codecov]

Codecov Report

Merging #2934 (e1ee5ca) into master (823adfc) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master    #2934   +/-   ##
=======================================
  Coverage   98.57%   98.57%           
=======================================
  Files          41       41           
  Lines        3080     3085    +5     
=======================================
+ Hits         3036     3041    +5     
  Misses         31       31           
  Partials       13       13           

Flag	Coverage Δ
go-1.13	∅ <ø> (∅)
go-1.14	∅ <ø> (∅)
go-1.15	∅ <ø> (∅)
go-1.16	98.57% <100.00%> (+<0.01%)	⬆️
go-1.17	98.47% <100.00%> (+<0.01%)	⬆️
macos-latest	98.57% <100.00%> (+<0.01%)	⬆️
nomsgpack	98.55% <100.00%> (+<0.01%)	⬆️
ubuntu-latest	98.57% <100.00%> (+<0.01%)	⬆️

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

Impacted Files	Coverage Δ
tree.go	100.00% <100.00%> (ø)

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 823adfc...e1ee5ca. Read the comment docs.

[SericaLaw]

@appleboy @thinkerou Hi, sorry to bother, any suggestions about this change and the diff coverage? I have no idea why my changes will remove coverage for debugPrintWARNINGDefault() func in debug.go.

[Bisstocuz]

@appleboy @thinkerou Hi, sorry to bother, any suggestions about this change and the diff coverage? I have no idea why my changes will remove coverage for debugPrintWARNINGDefault() func in debug.go.

Try to merge from upstream/master and check it again?

[Bisstocuz]

You may need to add some unit test cases for this change, too.

[thinkerou]

lgtm